code: def testIncorrectOperator(self):
      net = core.Net("test_net")
      a, b, one = net.AddExternalInput("a", "b", "one")
      m1 = net.Mul(a, b)  # does not have second output
      sub = net.Sub([m1, one])
      try:
          net.AddGradientOperators([sub])
          self.assertFalse(True, "Did not throw exception")
      except Exception as e:
          self.assertTrue("schema" in str(e))
  
imports: from hypothesis import given, settings
  import hypothesis.strategies
  import unittest
  from caffe2.proto import caffe2_pb2
  from caffe2.python import core, test_util, workspace
  from caffe2.python.core import CreateOperator, GradientRegistry, IR
  import numpy
label_desc: Use image node_id 10 for calling the TestGradientsAccumulationWithPassThroughGradients obj's underlying member method code with example usage: obj.testIncorrectOperator() without return types