code: def testMostSpecificFunctionCacheKeyIsLookedUp(self):
      ctx = function_cache.FunctionContext(0)
      cache = function_cache.FunctionCache()
      cache.add(
          MockFunction(
              make_single_param_type(MockShape(1, 2, None)), "a"
          ),
          ctx,
      )
      cache.add(
          MockFunction(make_single_param_type(MockShape(1, 2, 3)), "b"),
          ctx,
      )
  
      self.assertEqual(
          cache.lookup(
              make_single_param_type(MockShape(1, 2, 3)), ctx
          ).test_string,
          "b",
      )
  
imports: import dataclasses
  import itertools
  import timeit
  from typing import Any, Optional
  from tensorflow.core.function import trace_type
  from tensorflow.core.function.polymorphism import function_cache
  from tensorflow.core.function.polymorphism import function_type
  from tensorflow.python.ops import array_ops
  from tensorflow.python.platform import test
  from tensorflow.python.types import trace
label_desc: Use image node_id 4 for calling the FunctionCacheTest obj's underlying member method code with example usage: obj.testMostSpecificFunctionCacheKeyIsLookedUp() without return types