code: def _discarded_reads1_out_file_name(self):
          
          if self.Parameters['-3'].isOn():
              discarded_reads1 = self._absolute(str(self.Parameters['-3'].Value))
          else:
              raise ValueError(
                  "No discarded-reads1 (flag -3) output path specified")
          return discarded_reads1
docs: Checks if file name is set for discarded reads1 output.
             Returns absolute path.