code: def testUnknownShape(self):
      lengths = array_ops.placeholder(dtype=dtypes.int32)
      res = array_ops.sequence_mask(lengths)
      self.assertEqual(res.shape, None)
  
file_path: tensorflow-upstream/tensorflow/python/kernel_tests/v1_compat_tests/array_ops_test.py
imports: from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import errors
  from tensorflow.python.framework import tensor_shape
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import variable_v1
  from tensorflow.python.platform import test
label_desc: Use image node_id 1 for calling the SequenceMaskTest obj's underlying member method code with example usage: obj.testUnknownShape() without return types