code: def testStructIndexing(self):
      s = schema.Struct(
          ("field1", schema.Scalar(dtype=np.int32)),
          ("field2", schema.List(schema.Scalar(dtype=str))),
          ("field3", schema.Struct()),
      )
      self.assertEqual(s["field2"], s.field2)
      self.assertEqual(
          s["field2"], schema.List(schema.Scalar(dtype=str))
      )
      self.assertEqual(s["field3"], schema.Struct())
      self.assertEqual(
          s["field2", "field1"],
          schema.Struct(
              ("field2", schema.List(schema.Scalar(dtype=str))),
              ("field1", schema.Scalar(dtype=np.int32)),
          ),
      )
  
imports: from caffe2.python import core, schema
  import numpy
  import unittest
  import pickle
  import random
label_desc: Use image node_id 8 for calling the TestDB obj's underlying member method code with example usage: obj.testStructIndexing() without return types