code: def test_rank_known(self):
      with ops.Graph().as_default():
          x = array_ops.placeholder(dtypes.float32, [None, None])
          rank = pfor._rank(x)
          self.assertIsInstance(rank, int)
          self.assertEqual(rank, 2)
  
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 1 for calling the PForTest obj's underlying member method code with example usage: obj.test_rank_known() without return types