from tensorflow.python.framework import tensor_util

    """Helper which ensures that input is a non-negative, int32, scalar."""
    x = ops.convert_to_tensor(x, name="x")
    if x.dtype.base_dtype != dtypes.int32.base_dtype:
      raise TypeError("%s.dtype=%s is not %s" % (x.name, x.dtype, dtypes.int32))
    x_value_static = tensor_util.constant_value(x)
    if x.get_shape().ndims is not None and x_value_static is not None:
      if x.get_shape().ndims != 0:
        raise ValueError("%s.ndims=%d is not 0 (scalar)" %
