capybara/virtualenv/lib/python2.7/site-packages/lxml/html/diff.py
def cleanup_delete(chunks):
    """ Cleans up any DEL_START/DEL_END markers in the document, replacing
    them with <del></del>.  To do this while keeping the document
    valid, it may need to drop some tags (either start or end tags).

    It may also move the del into adjacent tags to try to move it to a
    similar location where it was originally located (e.g., moving a
    delete into preceding <div> tag, if the del looks like (DEL_START,
    'Text</div>', DEL_END)"""
    while 1:
        # Find a pending DEL_START/DEL_END, splitting the document
        # into stuff-preceding-DEL_START, stuff-inside, and
        # stuff-following-DEL_END
        try:
            pre_delete, delete, post_delete = split_delete(chunks)
        except NoDeletes:
            # Nothing found, we've cleaned up the entire doc
            break
        # The stuff-inside-DEL_START/END may not be well balanced
        # markup.  First we figure out what unbalanced portions there are:
        unbalanced_start, balanced, unbalanced_end = split_unbalanced(delete)
        # Then we move the span forward and/or backward based on these
        # unbalanced portions:
        locate_unbalanced_start(unbalanced_start, pre_delete, post_delete)
        locate_unbalanced_end(unbalanced_end, pre_delete, post_delete)
        doc = pre_delete
        if doc and not doc[-1].endswith(' '):
            # Fix up case where the word before us didn't have a trailing space
            doc[-1] += ' '
        doc.append('<del>')
        if balanced and balanced[-1].endswith(' '):
            # We move space outside of </del>
            balanced[-1] = balanced[-1][:-1]
        doc.extend(balanced)
        doc.append('</del> ')
        doc.extend(post_delete)
        chunks = doc
    return chunks
def cleanup_delete(chunks):
    """ Cleans up any DEL_START/DEL_END markers in the document, replacing
    them with <del></del>.  To do this while keeping the document
    valid, it may need to drop some tags (either start or end tags).

    It may also move the del into adjacent tags to try to move it to a
    similar location where it was originally located (e.g., moving a
    delete into preceding <div> tag, if the del looks like (DEL_START,
    'Text</div>', DEL_END)"""
    while 1:
        # Find a pending DEL_START/DEL_END, splitting the document
        # into stuff-preceding-DEL_START, stuff-inside, and
        # stuff-following-DEL_END
        try:
            pre_delete, delete, post_delete = split_delete(chunks)
        except NoDeletes:
            # Nothing found, we've cleaned up the entire doc
            break
        # The stuff-inside-DEL_START/END may not be well balanced
        # markup.  First we figure out what unbalanced portions there are:
        unbalanced_start, balanced, unbalanced_end = split_unbalanced(delete)
        # Then we move the span forward and/or backward based on these
        # unbalanced portions:
        locate_unbalanced_start(unbalanced_start, pre_delete, post_delete)
        locate_unbalanced_end(unbalanced_end, pre_delete, post_delete)
        doc = pre_delete
        if doc and not doc[-1].endswith(' '):
            # Fix up case where the word before us didn't have a trailing space
            doc[-1] += ' '
        doc.append('<del>')
        if balanced and balanced[-1].endswith(' '):
            # We move space outside of </del>
            balanced[-1] = balanced[-1][:-1]
        doc.extend(balanced)
        doc.append('</del> ')
        doc.extend(post_delete)
        chunks = doc
    return chunks
Cleans up any DEL_START/DEL_END markers in the document, replacing
    them with <del></del>.  To do this while keeping the document
    valid, it may need to drop some tags (either start or end tags).

    It may also move the del into adjacent tags to try to move it to a
    similar location where it was originally located (e.g., moving a
    delete into preceding <div> tag, if the del looks like (DEL_START,
    'Text</div>', DEL_END)