def has_antecedent(markable):
    """
    checks, if a markable has an antecedent. This function is only useful
    for Chiarcos-style MMAX projects, where anaphoric relations are marked
    as pointing relations between markables.

    Parameters
    ----------
    markable : etree._Element
        an etree element representing an MMAX markable

    Returns
    -------
    has_antecedent : bool
        Returns True, iff the markable has an antecedent.
    """
    return ('anaphor_antecedent' in markable.attrib
            and markable.attrib['anaphor_antecedent'] != 'empty')