def get_v_merge(tc):
    """
    vMerge is what docx uses to denote that a table cell is part of a rowspan.
    The first cell to have a vMerge is the start of the rowspan, and the vMerge
    will be denoted with 'restart'. If it is anything other than restart then
    it is a continuation of another rowspan.
    """
    if tc is None:
        return None
    v_merges = tc.xpath('.//w:vMerge', namespaces=tc.nsmap)
    if len(v_merges) != 1:
        return None
    v_merge = v_merges[0]
    return v_merge
vMerge is what docx uses to denote that a table cell is part of a rowspan.
    The first cell to have a vMerge is the start of the rowspan, and the vMerge
    will be denoted with 'restart'. If it is anything other than restart then
    it is a continuation of another rowspan.