code: def apply_set(self, ty):
          
          assert ty in ('jac0', 'jac')
  
          if ty == 'jac0':
              todo = ['Fx0', 'Fy0', 'Gx0', 'Gy0']
          else:
              todo = ['Fx', 'Fy', 'Gx', 'Gy']
  
          for m in todo:
              for idx in range(len(self._set[m]['I'])):
                  i = self._set[m]['I'][idx]
                  j = self._set[m]['J'][idx]
                  v = self._set[m]['V'][idx]
                  self.__dict__[m][i, j] = v
docs: Apply Jacobian set values to matrices
  
          :param ty: Jacobian type in ``('jac0', 'jac')``
          :return: