code: def knob_subgroup(self, cutoff=7.0):
          
          if cutoff > self.cutoff:
              raise ValueError("cutoff supplied ({0}) cannot be greater than self.cutoff ({1})".format(cutoff,
                                                                                                       self.cutoff))
          return KnobGroup(monomers=[x for x in self.get_monomers()
                                     if x.max_kh_distance <= cutoff], ampal_parent=self.ampal_parent)
docs: KnobGroup where all KnobsIntoHoles have max_kh_distance <= cutoff.