code: def test_call(self):
      seq = sequential.Sequential(
          [append_character(ch) for ch in "rocks!"]
      )
      self.assertEqual(seq("Sonnet "), "Sonnet rocks!")
  
file_path: sonnet/sonnet/src/sequential_test.py
imports: from absl.testing import parameterized
  from sonnet.src import sequential
  from sonnet.src import test_utils
  import tensorflow
label_desc: Use image node_id 4 for calling the SequentialTest obj's underlying member method code with example usage: obj.test_call() without return types