code: def update_ff(self, ff, mol2=False, force_ff_assign=False):
          
          aff = False
          if force_ff_assign:
              aff = True
          elif 'assigned_ff' not in self.tags:
              aff = True
          elif not self.tags['assigned_ff']:
              aff = True
          if aff:
              self.assign_force_field(ff, mol2=mol2)
          return
docs: Manages assigning the force field parameters.
  
          The aim of this method is to avoid unnecessary assignment of the
          force field.
  
          Parameters
          ----------
          ff: BuffForceField
              The force field to be used for scoring.
          mol2: bool, optional
              If true, mol2 style labels will also be used.
          force_ff_assign: bool, optional
              If true, the force field will be completely reassigned, ignoring the
              cached parameters.