code: def testUnknownRankError(self):
      if context.executing_eagerly():
          return
      s = array_ops.placeholder(dtypes.string)
      message = "Rank of `input` must be statically known."
      with self.assertRaisesRegex(ValueError, message):
          self.evaluate(
              ragged_string_ops.unicode_decode(
                  s, input_encoding="UTF-8"
              )
          )
  
imports: from absl.testing import parameterized
  import numpy
  from tensorflow.python.eager import context
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import errors
  from tensorflow.python.framework import sparse_tensor
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import gen_string_ops
  from tensorflow.python.ops.ragged import ragged_factory_ops
  from tensorflow.python.ops.ragged import ragged_string_ops
  from tensorflow.python.platform import test
label_desc: Use image node_id 15 for calling the UnicodeDecodeTest obj's underlying member method code with example usage: obj.testUnknownRankError() without return types