code: def parse_dtype_info(flags):
    
    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
docs: 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.