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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 fn_with_diet_vars(params):
 """Decorator for graph-building function to use diet variables."""

  params = copy.copy(params)

  def dec(fn):

    def wrapped(*args):
      return _fn_with_diet_vars(fn, args, params)

    return wrapped

  return dec