code: def replace_units(self, units, copy=True):
          
          _lock = self.lock
          if copy:
              pots = self.__class__()
          else:
              pots = self
  
          pots._units = None
          pots.lock = False
  
          for k, v in self.items():
              pots[k] = v.replace_units(units, copy=copy)
  
          pots.lock = _lock
          return pots
docs: Change the unit system of this potential.
  
          Parameters
          ----------
          units : `~gala.units.UnitSystem`
              Set of non-reducable units that specify (at minimum) the
              length, mass, time, and angle units.
          copy : bool (optional)
              If True, returns a copy, if False, changes this object.