code: def list_helper(self,k,pak,attr,col):
          
          # special case for horrible HFB6 exception
          # if type(pak) == flopy.modflow.mfhfb.ModflowHfb:
          #     filename = pak.file_name[0]
          # else:
          filename = attr.get_filename(k)
          filename_model = os.path.join(self.m.external_path,filename)
          shutil.copy2(os.path.join(self.m.model_ws,filename_model),
                       os.path.join(self.m.model_ws,self.list_org,filename))
          return filename_model
docs: helper to setup list multiplier parameters for a given
          k, pak, attr set.
  
          Parameters
          ----------
          k : int or iterable of int
              the zero-based stress period indices
          pak : flopy.PakBase=
              the MODFLOW package
          attr : MfList
              the MfList instance
          col : str
              the column name in the MfList recarray to parameterize