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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 final_energy(self):
 """ Final energy from the vasp run. """

        try:
            final_istep = self.ionic_steps[-1]
            if final_istep["e_wo_entrp"] != final_istep[
                'electronic_steps'][-1]["e_0_energy"]:
                warnings.warn("Final e_wo_entrp differs from the final "
                              "electronic step. VASP may have included some "
                              "corrections, e.g., vdw. Vasprun will return "
                              "the final e_wo_entrp, i.e., including "
                              "corrections in such instances.")
                return final_istep["e_wo_entrp"]
            return final_istep['electronic_steps'][-1]["e_0_energy"]
        except (IndexError, KeyError):
            warnings.warn("Calculation does not have a total energy. "
                          "Possibly a GW or similar kind of run. A value of "
                          "infinity is returned.")
            return float('inf')