code: def tensor_identity(x):
      assert isinstance(x, tf.Tensor)
      return x
  
file_path: sonnet/sonnet/src/build_test.py
imports: from sonnet.src import build
  from sonnet.src import test_utils
  import tensorflow
label_desc: Use image node_id 1 for calling a global function with example usage: tensor_identity(x) and returns: x