code: def _split_line(self, line):
          
          line = line.rstrip('\r\n')
          flds = re.split('\t', line)
          assert len(flds) == self.exp_numcol, "EXPECTED({E}) COLUMNS, ACTUAL({A}): {L}".format(
              E=self.exp_numcol, A=len(flds), L=line)
          return flds
docs: Split line into field values.