code: def _chk_qualifier(self, qualifiers, flds, lnum):
          
          # http://geneontology.org/page/go-annotation-conventions#qual
          for qual in qualifiers:
              if qual not in AnnoReaderBase.exp_qualifiers:
                  errname = 'UNEXPECTED QUALIFIER({QUAL})'.format(QUAL=qual)
                  self.illegal_lines[errname].append((lnum, "\t".join(flds)))
docs: Check that qualifiers are expected values.