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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 as_ufloat(roorealvar):
 """ Cast a `RooRealVar` to an `uncertainties.ufloat` """

    if isinstance(roorealvar, (U.AffineScalarFunc, U.Variable)):
        return roorealvar
    return U.ufloat((roorealvar.getVal(), roorealvar.getError()))