docs: def _unassembled_reads2_out_file_name(self):
          """Checks if file name is set for reads2 output.
             Returns absolute path."""
          if self.Parameters['-2'].isOn():
              unassembled_reads2 = self._absolute(
                  str(self.Parameters['-2'].Value))
          else:
              raise ValueError("No reads2 (flag -2) output path specified")
          return unassembled_reads2