Mercurial > repos > shellac > sam_consensus_v3
diff env/lib/python3.9/site-packages/bs4/__init__.py @ 0:4f3585e2f14b draft default tip
"planemo upload commit 60cee0fc7c0cda8592644e1aad72851dec82c959"
| author | shellac |
|---|---|
| date | Mon, 22 Mar 2021 18:12:50 +0000 |
| parents | |
| children |
line wrap: on
line diff
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/env/lib/python3.9/site-packages/bs4/__init__.py Mon Mar 22 18:12:50 2021 +0000 @@ -0,0 +1,791 @@ +"""Beautiful Soup Elixir and Tonic - "The Screen-Scraper's Friend". + +http://www.crummy.com/software/BeautifulSoup/ + +Beautiful Soup uses a pluggable XML or HTML parser to parse a +(possibly invalid) document into a tree representation. Beautiful Soup +provides methods and Pythonic idioms that make it easy to navigate, +search, and modify the parse tree. + +Beautiful Soup works with Python 2.7 and up. It works better if lxml +and/or html5lib is installed. + +For more than you ever wanted to know about Beautiful Soup, see the +documentation: http://www.crummy.com/software/BeautifulSoup/bs4/doc/ +""" + +__author__ = "Leonard Richardson (leonardr@segfault.org)" +__version__ = "4.9.3" +__copyright__ = "Copyright (c) 2004-2020 Leonard Richardson" +# Use of this source code is governed by the MIT license. +__license__ = "MIT" + +__all__ = ['BeautifulSoup'] + +from collections import Counter +import os +import re +import sys +import traceback +import warnings + +from .builder import builder_registry, ParserRejectedMarkup +from .dammit import UnicodeDammit +from .element import ( + CData, + Comment, + DEFAULT_OUTPUT_ENCODING, + Declaration, + Doctype, + NavigableString, + PageElement, + ProcessingInstruction, + PYTHON_SPECIFIC_ENCODINGS, + ResultSet, + Script, + Stylesheet, + SoupStrainer, + Tag, + TemplateString, + ) + +# The very first thing we do is give a useful error if someone is +# running this code under Python 3 without converting it. +'You are trying to run the Python 2 version of Beautiful Soup under Python 3. This will not work.'!='You need to convert the code, either by installing it (`python setup.py install`) or by running 2to3 (`2to3 -w bs4`).' + +# Define some custom warnings. +class GuessedAtParserWarning(UserWarning): + """The warning issued when BeautifulSoup has to guess what parser to + use -- probably because no parser was specified in the constructor. + """ + +class MarkupResemblesLocatorWarning(UserWarning): + """The warning issued when BeautifulSoup is given 'markup' that + actually looks like a resource locator -- a URL or a path to a file + on disk. + """ + + +class BeautifulSoup(Tag): + """A data structure representing a parsed HTML or XML document. + + Most of the methods you'll call on a BeautifulSoup object are inherited from + PageElement or Tag. + + Internally, this class defines the basic interface called by the + tree builders when converting an HTML/XML document into a data + structure. The interface abstracts away the differences between + parsers. To write a new tree builder, you'll need to understand + these methods as a whole. + + These methods will be called by the BeautifulSoup constructor: + * reset() + * feed(markup) + + The tree builder may call these methods from its feed() implementation: + * handle_starttag(name, attrs) # See note about return value + * handle_endtag(name) + * handle_data(data) # Appends to the current data node + * endData(containerClass) # Ends the current data node + + No matter how complicated the underlying parser is, you should be + able to build a tree using 'start tag' events, 'end tag' events, + 'data' events, and "done with data" events. + + If you encounter an empty-element tag (aka a self-closing tag, + like HTML's <br> tag), call handle_starttag and then + handle_endtag. + """ + + # Since BeautifulSoup subclasses Tag, it's possible to treat it as + # a Tag with a .name. This name makes it clear the BeautifulSoup + # object isn't a real markup tag. + ROOT_TAG_NAME = '[document]' + + # If the end-user gives no indication which tree builder they + # want, look for one with these features. + DEFAULT_BUILDER_FEATURES = ['html', 'fast'] + + # A string containing all ASCII whitespace characters, used in + # endData() to detect data chunks that seem 'empty'. + ASCII_SPACES = '\x20\x0a\x09\x0c\x0d' + + NO_PARSER_SPECIFIED_WARNING = "No parser was explicitly specified, so I'm using the best available %(markup_type)s parser for this system (\"%(parser)s\"). This usually isn't a problem, but if you run this code on another system, or in a different virtual environment, it may use a different parser and behave differently.\n\nThe code that caused this warning is on line %(line_number)s of the file %(filename)s. To get rid of this warning, pass the additional argument 'features=\"%(parser)s\"' to the BeautifulSoup constructor.\n" + + def __init__(self, markup="", features=None, builder=None, + parse_only=None, from_encoding=None, exclude_encodings=None, + element_classes=None, **kwargs): + """Constructor. + + :param markup: A string or a file-like object representing + markup to be parsed. + + :param features: Desirable features of the parser to be + used. This may be the name of a specific parser ("lxml", + "lxml-xml", "html.parser", or "html5lib") or it may be the + type of markup to be used ("html", "html5", "xml"). It's + recommended that you name a specific parser, so that + Beautiful Soup gives you the same results across platforms + and virtual environments. + + :param builder: A TreeBuilder subclass to instantiate (or + instance to use) instead of looking one up based on + `features`. You only need to use this if you've implemented a + custom TreeBuilder. + + :param parse_only: A SoupStrainer. Only parts of the document + matching the SoupStrainer will be considered. This is useful + when parsing part of a document that would otherwise be too + large to fit into memory. + + :param from_encoding: A string indicating the encoding of the + document to be parsed. Pass this in if Beautiful Soup is + guessing wrongly about the document's encoding. + + :param exclude_encodings: A list of strings indicating + encodings known to be wrong. Pass this in if you don't know + the document's encoding but you know Beautiful Soup's guess is + wrong. + + :param element_classes: A dictionary mapping BeautifulSoup + classes like Tag and NavigableString, to other classes you'd + like to be instantiated instead as the parse tree is + built. This is useful for subclassing Tag or NavigableString + to modify default behavior. + + :param kwargs: For backwards compatibility purposes, the + constructor accepts certain keyword arguments used in + Beautiful Soup 3. None of these arguments do anything in + Beautiful Soup 4; they will result in a warning and then be + ignored. + + Apart from this, any keyword arguments passed into the + BeautifulSoup constructor are propagated to the TreeBuilder + constructor. This makes it possible to configure a + TreeBuilder by passing in arguments, not just by saying which + one to use. + """ + if 'convertEntities' in kwargs: + del kwargs['convertEntities'] + warnings.warn( + "BS4 does not respect the convertEntities argument to the " + "BeautifulSoup constructor. Entities are always converted " + "to Unicode characters.") + + if 'markupMassage' in kwargs: + del kwargs['markupMassage'] + warnings.warn( + "BS4 does not respect the markupMassage argument to the " + "BeautifulSoup constructor. The tree builder is responsible " + "for any necessary markup massage.") + + if 'smartQuotesTo' in kwargs: + del kwargs['smartQuotesTo'] + warnings.warn( + "BS4 does not respect the smartQuotesTo argument to the " + "BeautifulSoup constructor. Smart quotes are always converted " + "to Unicode characters.") + + if 'selfClosingTags' in kwargs: + del kwargs['selfClosingTags'] + warnings.warn( + "BS4 does not respect the selfClosingTags argument to the " + "BeautifulSoup constructor. The tree builder is responsible " + "for understanding self-closing tags.") + + if 'isHTML' in kwargs: + del kwargs['isHTML'] + warnings.warn( + "BS4 does not respect the isHTML argument to the " + "BeautifulSoup constructor. Suggest you use " + "features='lxml' for HTML and features='lxml-xml' for " + "XML.") + + def deprecated_argument(old_name, new_name): + if old_name in kwargs: + warnings.warn( + 'The "%s" argument to the BeautifulSoup constructor ' + 'has been renamed to "%s."' % (old_name, new_name)) + value = kwargs[old_name] + del kwargs[old_name] + return value + return None + + parse_only = parse_only or deprecated_argument( + "parseOnlyThese", "parse_only") + + from_encoding = from_encoding or deprecated_argument( + "fromEncoding", "from_encoding") + + if from_encoding and isinstance(markup, str): + warnings.warn("You provided Unicode markup but also provided a value for from_encoding. Your from_encoding will be ignored.") + from_encoding = None + + self.element_classes = element_classes or dict() + + # We need this information to track whether or not the builder + # was specified well enough that we can omit the 'you need to + # specify a parser' warning. + original_builder = builder + original_features = features + + if isinstance(builder, type): + # A builder class was passed in; it needs to be instantiated. + builder_class = builder + builder = None + elif builder is None: + if isinstance(features, str): + features = [features] + if features is None or len(features) == 0: + features = self.DEFAULT_BUILDER_FEATURES + builder_class = builder_registry.lookup(*features) + if builder_class is None: + raise FeatureNotFound( + "Couldn't find a tree builder with the features you " + "requested: %s. Do you need to install a parser library?" + % ",".join(features)) + + # At this point either we have a TreeBuilder instance in + # builder, or we have a builder_class that we can instantiate + # with the remaining **kwargs. + if builder is None: + builder = builder_class(**kwargs) + if not original_builder and not ( + original_features == builder.NAME or + original_features in builder.ALTERNATE_NAMES + ) and markup: + # The user did not tell us which TreeBuilder to use, + # and we had to guess. Issue a warning. + if builder.is_xml: + markup_type = "XML" + else: + markup_type = "HTML" + + # This code adapted from warnings.py so that we get the same line + # of code as our warnings.warn() call gets, even if the answer is wrong + # (as it may be in a multithreading situation). + caller = None + try: + caller = sys._getframe(1) + except ValueError: + pass + if caller: + globals = caller.f_globals + line_number = caller.f_lineno + else: + globals = sys.__dict__ + line_number= 1 + filename = globals.get('__file__') + if filename: + fnl = filename.lower() + if fnl.endswith((".pyc", ".pyo")): + filename = filename[:-1] + if filename: + # If there is no filename at all, the user is most likely in a REPL, + # and the warning is not necessary. + values = dict( + filename=filename, + line_number=line_number, + parser=builder.NAME, + markup_type=markup_type + ) + warnings.warn( + self.NO_PARSER_SPECIFIED_WARNING % values, + GuessedAtParserWarning, stacklevel=2 + ) + else: + if kwargs: + warnings.warn("Keyword arguments to the BeautifulSoup constructor will be ignored. These would normally be passed into the TreeBuilder constructor, but a TreeBuilder instance was passed in as `builder`.") + + self.builder = builder + self.is_xml = builder.is_xml + self.known_xml = self.is_xml + self._namespaces = dict() + self.parse_only = parse_only + + self.builder.initialize_soup(self) + + if hasattr(markup, 'read'): # It's a file-type object. + markup = markup.read() + elif len(markup) <= 256 and ( + (isinstance(markup, bytes) and not b'<' in markup) + or (isinstance(markup, str) and not '<' in markup) + ): + # Print out warnings for a couple beginner problems + # involving passing non-markup to Beautiful Soup. + # Beautiful Soup will still parse the input as markup, + # just in case that's what the user really wants. + if (isinstance(markup, str) + and not os.path.supports_unicode_filenames): + possible_filename = markup.encode("utf8") + else: + possible_filename = markup + is_file = False + try: + is_file = os.path.exists(possible_filename) + except Exception as e: + # This is almost certainly a problem involving + # characters not valid in filenames on this + # system. Just let it go. + pass + if is_file: + warnings.warn( + '"%s" looks like a filename, not markup. You should' + ' probably open this file and pass the filehandle into' + ' Beautiful Soup.' % self._decode_markup(markup), + MarkupResemblesLocatorWarning + ) + self._check_markup_is_url(markup) + + rejections = [] + success = False + for (self.markup, self.original_encoding, self.declared_html_encoding, + self.contains_replacement_characters) in ( + self.builder.prepare_markup( + markup, from_encoding, exclude_encodings=exclude_encodings)): + self.reset() + try: + self._feed() + success = True + break + except ParserRejectedMarkup as e: + rejections.append(e) + pass + + if not success: + other_exceptions = [str(e) for e in rejections] + raise ParserRejectedMarkup( + "The markup you provided was rejected by the parser. Trying a different parser or a different encoding may help.\n\nOriginal exception(s) from parser:\n " + "\n ".join(other_exceptions) + ) + + # Clear out the markup and remove the builder's circular + # reference to this object. + self.markup = None + self.builder.soup = None + + def __copy__(self): + """Copy a BeautifulSoup object by converting the document to a string and parsing it again.""" + copy = type(self)( + self.encode('utf-8'), builder=self.builder, from_encoding='utf-8' + ) + + # Although we encoded the tree to UTF-8, that may not have + # been the encoding of the original markup. Set the copy's + # .original_encoding to reflect the original object's + # .original_encoding. + copy.original_encoding = self.original_encoding + return copy + + def __getstate__(self): + # Frequently a tree builder can't be pickled. + d = dict(self.__dict__) + if 'builder' in d and not self.builder.picklable: + d['builder'] = None + return d + + @classmethod + def _decode_markup(cls, markup): + """Ensure `markup` is bytes so it's safe to send into warnings.warn. + + TODO: warnings.warn had this problem back in 2010 but it might not + anymore. + """ + if isinstance(markup, bytes): + decoded = markup.decode('utf-8', 'replace') + else: + decoded = markup + return decoded + + @classmethod + def _check_markup_is_url(cls, markup): + """Error-handling method to raise a warning if incoming markup looks + like a URL. + + :param markup: A string. + """ + if isinstance(markup, bytes): + space = b' ' + cant_start_with = (b"http:", b"https:") + elif isinstance(markup, str): + space = ' ' + cant_start_with = ("http:", "https:") + else: + return + + if any(markup.startswith(prefix) for prefix in cant_start_with): + if not space in markup: + warnings.warn( + '"%s" looks like a URL. Beautiful Soup is not an' + ' HTTP client. You should probably use an HTTP client like' + ' requests to get the document behind the URL, and feed' + ' that document to Beautiful Soup.' % cls._decode_markup( + markup + ), + MarkupResemblesLocatorWarning + ) + + def _feed(self): + """Internal method that parses previously set markup, creating a large + number of Tag and NavigableString objects. + """ + # Convert the document to Unicode. + self.builder.reset() + + self.builder.feed(self.markup) + # Close out any unfinished strings and close all the open tags. + self.endData() + while self.currentTag.name != self.ROOT_TAG_NAME: + self.popTag() + + def reset(self): + """Reset this object to a state as though it had never parsed any + markup. + """ + Tag.__init__(self, self, self.builder, self.ROOT_TAG_NAME) + self.hidden = 1 + self.builder.reset() + self.current_data = [] + self.currentTag = None + self.tagStack = [] + self.open_tag_counter = Counter() + self.preserve_whitespace_tag_stack = [] + self.string_container_stack = [] + self.pushTag(self) + + def new_tag(self, name, namespace=None, nsprefix=None, attrs={}, + sourceline=None, sourcepos=None, **kwattrs): + """Create a new Tag associated with this BeautifulSoup object. + + :param name: The name of the new Tag. + :param namespace: The URI of the new Tag's XML namespace, if any. + :param prefix: The prefix for the new Tag's XML namespace, if any. + :param attrs: A dictionary of this Tag's attribute values; can + be used instead of `kwattrs` for attributes like 'class' + that are reserved words in Python. + :param sourceline: The line number where this tag was + (purportedly) found in its source document. + :param sourcepos: The character position within `sourceline` where this + tag was (purportedly) found. + :param kwattrs: Keyword arguments for the new Tag's attribute values. + + """ + kwattrs.update(attrs) + return self.element_classes.get(Tag, Tag)( + None, self.builder, name, namespace, nsprefix, kwattrs, + sourceline=sourceline, sourcepos=sourcepos + ) + + def string_container(self, base_class=None): + container = base_class or NavigableString + + # There may be a general override of NavigableString. + container = self.element_classes.get( + container, container + ) + + # On top of that, we may be inside a tag that needs a special + # container class. + if self.string_container_stack: + container = self.builder.string_containers.get( + self.string_container_stack[-1].name, container + ) + return container + + def new_string(self, s, subclass=None): + """Create a new NavigableString associated with this BeautifulSoup + object. + """ + container = self.string_container(subclass) + return container(s) + + def insert_before(self, *args): + """This method is part of the PageElement API, but `BeautifulSoup` doesn't implement + it because there is nothing before or after it in the parse tree. + """ + raise NotImplementedError("BeautifulSoup objects don't support insert_before().") + + def insert_after(self, *args): + """This method is part of the PageElement API, but `BeautifulSoup` doesn't implement + it because there is nothing before or after it in the parse tree. + """ + raise NotImplementedError("BeautifulSoup objects don't support insert_after().") + + def popTag(self): + """Internal method called by _popToTag when a tag is closed.""" + tag = self.tagStack.pop() + if tag.name in self.open_tag_counter: + self.open_tag_counter[tag.name] -= 1 + if self.preserve_whitespace_tag_stack and tag == self.preserve_whitespace_tag_stack[-1]: + self.preserve_whitespace_tag_stack.pop() + if self.string_container_stack and tag == self.string_container_stack[-1]: + self.string_container_stack.pop() + #print("Pop", tag.name) + if self.tagStack: + self.currentTag = self.tagStack[-1] + return self.currentTag + + def pushTag(self, tag): + """Internal method called by handle_starttag when a tag is opened.""" + #print("Push", tag.name) + if self.currentTag is not None: + self.currentTag.contents.append(tag) + self.tagStack.append(tag) + self.currentTag = self.tagStack[-1] + if tag.name != self.ROOT_TAG_NAME: + self.open_tag_counter[tag.name] += 1 + if tag.name in self.builder.preserve_whitespace_tags: + self.preserve_whitespace_tag_stack.append(tag) + if tag.name in self.builder.string_containers: + self.string_container_stack.append(tag) + + def endData(self, containerClass=None): + """Method called by the TreeBuilder when the end of a data segment + occurs. + """ + containerClass = self.string_container(containerClass) + + if self.current_data: + current_data = ''.join(self.current_data) + # If whitespace is not preserved, and this string contains + # nothing but ASCII spaces, replace it with a single space + # or newline. + if not self.preserve_whitespace_tag_stack: + strippable = True + for i in current_data: + if i not in self.ASCII_SPACES: + strippable = False + break + if strippable: + if '\n' in current_data: + current_data = '\n' + else: + current_data = ' ' + + # Reset the data collector. + self.current_data = [] + + # Should we add this string to the tree at all? + if self.parse_only and len(self.tagStack) <= 1 and \ + (not self.parse_only.text or \ + not self.parse_only.search(current_data)): + return + + o = containerClass(current_data) + self.object_was_parsed(o) + + def object_was_parsed(self, o, parent=None, most_recent_element=None): + """Method called by the TreeBuilder to integrate an object into the parse tree.""" + if parent is None: + parent = self.currentTag + if most_recent_element is not None: + previous_element = most_recent_element + else: + previous_element = self._most_recent_element + + next_element = previous_sibling = next_sibling = None + if isinstance(o, Tag): + next_element = o.next_element + next_sibling = o.next_sibling + previous_sibling = o.previous_sibling + if previous_element is None: + previous_element = o.previous_element + + fix = parent.next_element is not None + + o.setup(parent, previous_element, next_element, previous_sibling, next_sibling) + + self._most_recent_element = o + parent.contents.append(o) + + # Check if we are inserting into an already parsed node. + if fix: + self._linkage_fixer(parent) + + def _linkage_fixer(self, el): + """Make sure linkage of this fragment is sound.""" + + first = el.contents[0] + child = el.contents[-1] + descendant = child + + if child is first and el.parent is not None: + # Parent should be linked to first child + el.next_element = child + # We are no longer linked to whatever this element is + prev_el = child.previous_element + if prev_el is not None and prev_el is not el: + prev_el.next_element = None + # First child should be linked to the parent, and no previous siblings. + child.previous_element = el + child.previous_sibling = None + + # We have no sibling as we've been appended as the last. + child.next_sibling = None + + # This index is a tag, dig deeper for a "last descendant" + if isinstance(child, Tag) and child.contents: + descendant = child._last_descendant(False) + + # As the final step, link last descendant. It should be linked + # to the parent's next sibling (if found), else walk up the chain + # and find a parent with a sibling. It should have no next sibling. + descendant.next_element = None + descendant.next_sibling = None + target = el + while True: + if target is None: + break + elif target.next_sibling is not None: + descendant.next_element = target.next_sibling + target.next_sibling.previous_element = child + break + target = target.parent + + def _popToTag(self, name, nsprefix=None, inclusivePop=True): + """Pops the tag stack up to and including the most recent + instance of the given tag. + + If there are no open tags with the given name, nothing will be + popped. + + :param name: Pop up to the most recent tag with this name. + :param nsprefix: The namespace prefix that goes with `name`. + :param inclusivePop: It this is false, pops the tag stack up + to but *not* including the most recent instqance of the + given tag. + + """ + #print("Popping to %s" % name) + if name == self.ROOT_TAG_NAME: + # The BeautifulSoup object itself can never be popped. + return + + most_recently_popped = None + + stack_size = len(self.tagStack) + for i in range(stack_size - 1, 0, -1): + if not self.open_tag_counter.get(name): + break + t = self.tagStack[i] + if (name == t.name and nsprefix == t.prefix): + if inclusivePop: + most_recently_popped = self.popTag() + break + most_recently_popped = self.popTag() + + return most_recently_popped + + def handle_starttag(self, name, namespace, nsprefix, attrs, sourceline=None, + sourcepos=None): + """Called by the tree builder when a new tag is encountered. + + :param name: Name of the tag. + :param nsprefix: Namespace prefix for the tag. + :param attrs: A dictionary of attribute values. + :param sourceline: The line number where this tag was found in its + source document. + :param sourcepos: The character position within `sourceline` where this + tag was found. + + If this method returns None, the tag was rejected by an active + SoupStrainer. You should proceed as if the tag had not occurred + in the document. For instance, if this was a self-closing tag, + don't call handle_endtag. + """ + # print("Start tag %s: %s" % (name, attrs)) + self.endData() + + if (self.parse_only and len(self.tagStack) <= 1 + and (self.parse_only.text + or not self.parse_only.search_tag(name, attrs))): + return None + + tag = self.element_classes.get(Tag, Tag)( + self, self.builder, name, namespace, nsprefix, attrs, + self.currentTag, self._most_recent_element, + sourceline=sourceline, sourcepos=sourcepos + ) + if tag is None: + return tag + if self._most_recent_element is not None: + self._most_recent_element.next_element = tag + self._most_recent_element = tag + self.pushTag(tag) + return tag + + def handle_endtag(self, name, nsprefix=None): + """Called by the tree builder when an ending tag is encountered. + + :param name: Name of the tag. + :param nsprefix: Namespace prefix for the tag. + """ + #print("End tag: " + name) + self.endData() + self._popToTag(name, nsprefix) + + def handle_data(self, data): + """Called by the tree builder when a chunk of textual data is encountered.""" + self.current_data.append(data) + + def decode(self, pretty_print=False, + eventual_encoding=DEFAULT_OUTPUT_ENCODING, + formatter="minimal"): + """Returns a string or Unicode representation of the parse tree + as an HTML or XML document. + + :param pretty_print: If this is True, indentation will be used to + make the document more readable. + :param eventual_encoding: The encoding of the final document. + If this is None, the document will be a Unicode string. + """ + if self.is_xml: + # Print the XML declaration + encoding_part = '' + if eventual_encoding in PYTHON_SPECIFIC_ENCODINGS: + # This is a special Python encoding; it can't actually + # go into an XML document because it means nothing + # outside of Python. + eventual_encoding = None + if eventual_encoding != None: + encoding_part = ' encoding="%s"' % eventual_encoding + prefix = '<?xml version="1.0"%s?>\n' % encoding_part + else: + prefix = '' + if not pretty_print: + indent_level = None + else: + indent_level = 0 + return prefix + super(BeautifulSoup, self).decode( + indent_level, eventual_encoding, formatter) + +# Aliases to make it easier to get started quickly, e.g. 'from bs4 import _soup' +_s = BeautifulSoup +_soup = BeautifulSoup + +class BeautifulStoneSoup(BeautifulSoup): + """Deprecated interface to an XML parser.""" + + def __init__(self, *args, **kwargs): + kwargs['features'] = 'xml' + warnings.warn( + 'The BeautifulStoneSoup class is deprecated. Instead of using ' + 'it, pass features="xml" into the BeautifulSoup constructor.') + super(BeautifulStoneSoup, self).__init__(*args, **kwargs) + + +class StopParsing(Exception): + """Exception raised by a TreeBuilder if it's unable to continue parsing.""" + pass + +class FeatureNotFound(ValueError): + """Exception raised by the BeautifulSoup constructor if no parser with the + requested features is found. + """ + pass + + +#If this file is run as a script, act as an HTML pretty-printer. +if __name__ == '__main__': + import sys + soup = BeautifulSoup(sys.stdin) + print((soup.prettify()))