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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 alphabetical_formula(self):
 """ Returns a reduced formula string with appended charge """

        alph_formula = super().alphabetical_formula
        chg_str = ""
        if self.charge > 0:
            chg_str = " +" + formula_double_format(self.charge, False)
        elif self.charge < 0:
            chg_str = " " + formula_double_format(self.charge, False)
        return alph_formula + chg_str