code: def create_system(self, **system_options):
          
          if self.master is None:
              raise ValueError('Handler {} is not able to create systems.'.format(self))
  
          if isinstance(self.master, ForceField):
              system = self.master.createSystem(self.topology, **system_options)
          elif isinstance(self.master, (AmberPrmtopFile, GromacsTopFile, DesmondDMSFile)):
              system = self.master.createSystem(**system_options)
          elif isinstance(self.master, CharmmPsfFile):
              if not hasattr(self.master, 'parmset'):
                  raise ValueError('PSF topology files require Charmm parameters.')
              system = self.master.createSystem(self.master.parmset, **system_options)
          else:
              raise NotImplementedError('Handler {} is not able to create systems.'.format(self))
  
          if self.has_box:
              system.setDefaultPeriodicBoxVectors(*self.box)
          return system
docs: Create an OpenMM system for every supported topology file with given system options