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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def map_(input_layer, fn):
 """Maps the given function across this sequence. To map an entire template across the sequence, use the `as_fn` method on the template. Args: input_layer: The input tensor. fn: A function of 1 argument that is applied to each item in the sequence. Returns: A new sequence Pretty Tensor. Raises: ValueError: If the input_layer does not hold a sequence. """

  if not input_layer.is_sequence():
    raise ValueError('Can only map a sequence.')
  return [fn(x) for x in input_layer]