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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 common_ancestor(c):
 """Return the path to the root that is shared between a binary-Mention Candidate. In particular, this is the common path of HTML tags. :param c: The binary-Mention Candidate to evaluate :rtype: list of strings """

    span1 = _to_span(c[0])
    span2 = _to_span(c[1])
    ancestor1 = np.array(span1.sentence.xpath.split("/"))
    ancestor2 = np.array(span2.sentence.xpath.split("/"))
    min_len = min(ancestor1.size, ancestor2.size)
    return list(ancestor1[: np.argmin(ancestor1[:min_len] == ancestor2[:min_len])])