<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:

def read_metadata(self, symbol):
        '''
        Reads user defined metadata out for the given symbol

        Parameters
        ----------
        symbol: str
            symbol for the given item in the DB

        Returns
        -------
        ?
        '''
        sym = self._get_symbol_info(symbol)
        if not sym:
            raise NoDataFoundException("Symbol does not exist.")
        x = self._symbols.find_one({SYMBOL: symbol})
        return x[USERMETA] if USERMETA in x else None