code: def alphabetical_formula(self):
          
          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
docs: Returns a reduced formula string with appended charge