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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 group_symbol(self):
 """Current group symbol. :getter: Returns current group symbol :setter: Sets current group symbol :type: str """

        s_mapping = {symdata.index: symdata.symbol for symdata in self._symboldata_list}
        return s_mapping[self.group_num]