code: def _suffix(self):
          
          _output_formats={'GCG':'.msf',
                          'GDE':'.gde',
                          'PHYLIP':'.phy',
                          'PIR':'.pir',
                          'NEXUS':'.nxs'}
  
          if self.Parameters['-output'].isOn():
              return _output_formats[self.Parameters['-output'].Value]
          else:
              return '.aln'
docs: Return appropriate suffix for alignment file