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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 create_from_eflux(cls, params, emin, emax, eflux, scale=1.0):
 """Create a spectral function instance given its energy flux."""

        params = params.copy()
        params[0] = 1.0
        params[0] = eflux / cls.eval_eflux(emin, emax, params, scale=scale)
        return cls(params, scale)