code: def test_non_tensor_variable_input_no_cast_func(self):
      mixed_precision.enable(tf.float32)
  
      @mixed_precision.modes([tf.float32, tf.float16])
      def fwd_func(x):
          self.assertEqual(type(x[0][0]), float)
          return x
  
      x = [[1.0, 3], [5.0, 7.0]]
      self.assertEqual(type(x[0][0]), float)
  
      mixed_precision.enable(tf.float16)
      self.assertEqual(type(fwd_func(x)[0][0]), float)
      self.assertEqual(type(fwd_func(x)[0][0]), float)
  
imports: from absl.testing import parameterized
  from sonnet.src import base
  from sonnet.src import mixed_precision
  from sonnet.src import test_utils
  import tensorflow
  import tree
label_desc: Use image node_id 5 for calling the MixedPrecisionTest obj's underlying member method code with example usage: obj.test_non_tensor_variable_input_no_cast_func() and returns: x