docs: def read_history(self, symbol):
          """
          Return all metadata saved for `symbol`
  
          Parameters
          ----------
          symbol : `str`
              symbol name for the item
  
          Returns
          -------
          pandas.DateFrame containing timestamps and metadata entries
          """
          find = self.find({'symbol': symbol}, sort=[('start_time', pymongo.ASCENDING)])
          times = []
          entries = []
          for item in find:
              times.append(item['start_time'])
              entries.append(item['metadata'])
          return pd.DataFrame({symbol: entries}, times)