code: def _prepare_padding_argument(x):
      """Helper which processes the padding argument."""
      if not hasattr(x, "upper"):
          return tuple(x)
      padding = x.upper()
      if padding in {"CAUSAL", "FULL"}:
          raise NotImplementedError(
              'Argument `padding` value "{}" currently not supported. If you '
              "require this feature, please create an issue on "
              "`https://github.com/tensorflow/probability` or email "
              "`tfprobability@tensorflow.org`.".format(padding)
          )
      valid_values = {"VALID", "SAME"}
      if padding not in valid_values:
          raise ValueError(
              "Argument `padding` must be convertible to a tuple "
              'or one of {}; saw: "{}".'.format(valid_values, padding)
          )
      return padding
  
imports: import tensorflow.compat.v2
  from tensorflow_probability.python.experimental.nn.util import utils
  from tensorflow_probability.python.internal import assert_util
  from tensorflow_probability.python.internal import dtype_util
  from tensorflow_probability.python.internal import prefer_static
label_desc: Use image node_id 16 for calling a global function with example usage: _prepare_padding_argument(x) and returns: padding, tuple