code: def test_size_unknown(self):
      with ops.Graph().as_default():
          x = array_ops.placeholder(dtypes.float32, [3, None])
  
          size = pfor._size(x, dtypes.int32)
          self.assertIsInstance(size, tensor.Tensor)
          self.assertEqual(size.dtype, dtypes.int32)
  
          size = pfor._size(x, dtypes.int64)
          self.assertIsInstance(size, tensor.Tensor)
          self.assertEqual(size.dtype, dtypes.int64)
  
file_path: tensorflow/tensorflow/python/ops/parallel_for/pfor_test.py
imports: from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import tensor
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import random_ops
  from tensorflow.python.ops.parallel_for import pfor
  from tensorflow.python.platform import test
label_desc: Use image node_id 4 for calling the PForTest obj's underlying member method code with example usage: obj.test_size_unknown() without return types