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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def space_labels(document):
 """Ensure space around bold compound labels."""

    for label in document.xpath('.//bold'):
        # TODO: Make this more permissive to match chemical_label in parser
        if not label.text or not re.match('^\(L?\d\d?[a-z]?\):?$', label.text, re.I):
            continue
        parent = label.getparent()
        previous = label.getprevious()
        if previous is None:
            text = parent.text or ''
            if not text.endswith(' '):
                parent.text = text + ' '
        else:
            text = previous.tail or ''
            if not text.endswith(' '):
                previous.tail = text + ' '
        text = label.tail or ''
        if not text.endswith(' '):
            label.tail = text + ' '
    return document