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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 parse_dtype_info(flags):
 """Convert dtype string to tf dtype, and set loss_scale default as needed. Args: flags: namespace object returned by arg parser. Raises: ValueError: If an invalid dtype is provided. """

  if flags.dtype in (i[0] for i in DTYPE_MAP.values()):
    return  # Make function idempotent

  try:
    flags.dtype, default_loss_scale = DTYPE_MAP[flags.dtype]
  except KeyError:
    raise ValueError("Invalid dtype: {}".format(flags.dtype))

  flags.loss_scale = flags.loss_scale or default_loss_scale