code: def test_wrong_rval_len1(self):
      # Test that it is not ok to return the wrong number of gradient terms
  
      class retOne(gof.op.Op):
          __props__ = ()
  
          def make_node(self, *inputs):
              outputs = [theano.tensor.vector()]
              return gof.Apply(self, inputs, outputs)
  
          def grad(self, inputs, grads):
              return [inputs[0].zeros_like()]
  
      i = theano.tensor.vector()
      j = theano.tensor.vector()
      a1 = retOne().make_node(i)
      grad_sources_inputs([(a1.out, one)], None)
      a2 = retOne().make_node(i, j)
      self.assertRaises(
          ValueError, grad_sources_inputs, [(a2.out, one)], None
      )
  
imports: from __future__ import absolute_import, print_function, division
  from collections import OrderedDict
  import unittest
  import numpy
  from six.moves import xrange
  import theano
  from theano import gof, change_flags
  from theano.compat import izip
  from theano.tests import unittest_tools
  from theano import gradient
  from theano import config
  from theano.gof.null_type import NullType
  from theano.sandbox.rng_mrg import MRG_RandomStreams
label_desc: Use image node_id 2 for calling the testgrad_sources_inputs obj's underlying member method code with example usage: obj.test_wrong_rval_len1() and returns: gof, list