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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 get_parent_tag(mention):
 """Return the HTML tag of the Mention's parent. These may be tags such as 'p', 'h2', 'table', 'div', etc. If a candidate is passed in, only the tag of its first Mention is returned. :param mention: The Mention to evaluate :rtype: string """

    span = _to_span(mention)
    i = _get_node(span.sentence)
    return str(i.getparent().tag) if i.getparent() is not None else None