code: def merge_qot_mkt_stock_str(qot_mkt, partial_stock_str):
      
      market_str = QUOTE.REV_MKT_MAP[qot_mkt]
      stock_str = '.'.join([market_str, partial_stock_str])
      return stock_str
docs: Merge the string of stocks
      :param market: market code
      :param partial_stock_str: original stock code string. i.e. "AAPL","00700", "000001"
      :return: unified representation of a stock code. i.e. "US.AAPL", "HK.00700", "SZ.000001"