code: def derivative(self, x):
          
          return BroadcastOperator(*[op.derivative(x) for op in
                                     self.operators])
docs: Derivative of the broadcast operator.
  
          Parameters
          ----------
          x : `domain` element
              The point to take the derivative in
  
          Returns
          -------
          adjoint : linear `BroadcastOperator`
              The derivative
  
          Examples
          --------
          Example with an affine operator:
  
          >>> I = odl.IdentityOperator(odl.rn(3))
          >>> residual_op = I - I.domain.element([1, 1, 1])
          >>> op = BroadcastOperator(residual_op, 2 * residual_op)
  
          Calling operator offsets by ``[1, 1, 1]``:
  
          >>> x = [1, 2, 3]
          >>> op(x)
          ProductSpace(rn(3), 2).element([
              [ 0.,  1.,  2.],
              [ 0.,  2.,  4.]
          ])
  
          The derivative of this affine operator does not have an offset:
  
          >>> op.derivative(x)(x)
          ProductSpace(rn(3), 2).element([
              [ 1.,  2.,  3.],
              [ 2.,  4.,  6.]
          ])