code: def testArgsExpansion(self):
      def foo(a, b):
          return a + b
  
      t = structural_tuple.structtuple(["c", "d"])
  
      self.assertEqual(3, nest_util.call_fn(foo, t(1, 2)))
  
imports: import tensorflow.compat.v2
  from tensorflow_probability.python.internal import nest_util
  from tensorflow_probability.python.internal import structural_tuple
  from tensorflow_probability.python.internal import test_util
  from tensorflow.python.util import nest
label_desc: Use image node_id 6 for calling the StructTupleTest obj's underlying member method code with example usage: obj.testArgsExpansion() and returns: unknown