class_docstr: Test of base registry.Registry class.
class_docstr_tok: ["Test","of","base","registry.Registry","class","."]
code: def testLen(self):
      r = registry.Registry("test_registry")
      self.assertEqual(len(r), 0)
      r["a"] = lambda: None
      self.assertEqual(len(r), 1)
      r["b"] = lambda: 4
      self.assertEqual(len(r), 2)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from tensor2tensor.utils import registry
  from tensor2tensor.utils import t2t_model
  import tensorflow.compat.v1
label_desc: Use image node_id 6 for calling the RegistryClassTest obj's underlying member method code with example usage: obj.testLen() without return types