Return fieldnames of either a namedtuple or GOEnrichmentRecord.

def _get_fieldnames(item):
        """Return fieldnames of either a namedtuple or GOEnrichmentRecord."""
        if hasattr(item, "_fldsdefprt"): # Is a GOEnrichmentRecord
            return item.get_prtflds_all()
        if hasattr(item, "_fields"): # Is a namedtuple
            return item._fields