code: def testStructAddition(self):
      s1 = schema.Struct(("a", schema.Scalar()))
      s2 = schema.Struct(("b", schema.Scalar()))
      s = s1 + s2
      self.assertIn("a", s.fields)
      self.assertIn("b", s.fields)
      with self.assertRaises(TypeError):
          s1 + s1
      with self.assertRaises(TypeError):
          s1 + schema.Scalar()
  
imports: from caffe2.python import core, schema
  import numpy
  import unittest
  import pickle
  import random
label_desc: Use image node_id 18 for calling the TestDB obj's underlying member method code with example usage: obj.testStructAddition() without return types