def _fill_shape(x, n):
  """Converts a dimension to a tuple of dimensions of a given size.

  This is used to allow shorthand notation for various configuration parameters.
  A user can provide either, for example, `2` or `[2, 2]` as a kernel shape, and
  this function returns `(2, 2)` in both cases. Passing `[1, 2]` will return
  `(1, 2)`.

  Args:
    x: An integer, tf.Dimension, or an iterable of them.
    n: An integer, the size of the desired output list

  Returns:
    If `x` is an integer, a tuple of size `n` containing `n` copies of `x`.
    If `x` is an iterable of integers or tf.Dimension of size `n`, it returns
      `tuple(x)`.

  Raises:
    TypeError: If n is not a positive integer;
      or if x is neither integer nor an iterable of size n.
  """
  if not isinstance(n, numbers.Integral) or n < 1:
    raise TypeError("n must be a positive integer")

  if (isinstance(x, numbers.Integral) or isinstance(x, tf.Dimension)) and x > 0:
    return (x,) * n

  try:
    if len(x) == n and all(v > 0 for v in x):
      return tuple(x)
  except TypeError:
    pass

  raise TypeError("x is {}, must be either a positive integer "
                  "or an iterable of positive integers of size {}"
                  .format(x, n))