<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def fix_symbol(self, symbol, reverse=False):
 """ In comes a moneywagon format symbol, and returned in the symbol converted to one the service can understand. """

        if not self.symbol_mapping:
            return symbol

        for old, new in self.symbol_mapping:
            if reverse:
                if symbol == new:
                    return old
            else:
                if symbol == old:
                    return new

        return symbol