def find_symbol(self, string, market=None):
    if (market is None):
        market = self.find_market(string)
    if isinstance(market, dict):
        return market['symbol']
    return string
def find_symbol(self, string, market=None):
    if (market is None):
        market = self.find_market(string)
    if isinstance(market, dict):
        return market['symbol']
    return string