Check that all fields in the prtfmt have corresponding data in the namedtuple.

def _chk_flds_fmt(nt_fields, prtfmt):
    """Check that all fields in the prtfmt have corresponding data in the namedtuple."""
    fmtflds = get_fmtflds(prtfmt)
    missing_data = set(fmtflds).difference(set(nt_fields))
    # All data needed for print is present, return.
    if not missing_data:
        return
    #raise Exception('MISSING DATA({M}).'.format(M=" ".join(missing_data)))
    msg = ['CANNOT PRINT USING: "{PF}"'.format(PF=prtfmt.rstrip())]
    for fld in fmtflds:
        errmrk = "" if fld in nt_fields else "ERROR-->"
        msg.append("  {ERR:8} {FLD}".format(ERR=errmrk, FLD=fld))
    raise Exception('\n'.join(msg))