def callproc(self, procname, parameters=(), quiet=False, expect_return_value=False):
        self.procedures_run += 1
        i = 0
        errcode = 0
        caughte = None
        out_param_indices = []
        for j in range(len(parameters)):
            p = parameters[j]
            if type(p) == type('') and p[0] == '@':
                assert(p.find(' ') == -1)
                out_param_indices.append(j)
        if procname not in self.list_stored_procedures():
            raise Exception("The stored procedure '%s' does not exist." % procname)
        if not re.match("^\s*\w+\s*$", procname):
            raise Exception("Expected a stored procedure name in callproc but received '%s'." % procname)
        while i < self.numTries:
            i += 1
            try:
                self._get_connection()
                cursor = self.connection.cursor()
                if type(parameters) != type(()):
                    parameters = (parameters,)
                errcode = cursor.callproc(procname, parameters)
                self.lastrowid = int(cursor.lastrowid)
                cursor.close()
                out_param_results = []
                if out_param_indices:
                    out_param_results = self.execute('SELECT %s' % ", ".join(['@_%s_%d AS %s' % (procname, pindex, parameters[pindex][1:]) for pindex in out_param_indices]))
                return out_param_results
            except MySQLdb.OperationalError, e:
                self._close_connection()
                errcode = e[0]
                caughte = e
                continue
            except:
                self._close_connection()
                traceback.print_exc()
                break
        if not quiet:
            sys.stderr.write("\nSQL execution error call stored procedure %s at %s:" % (
            procname, datetime.now().strftime("%Y-%m-%d %H:%M:%S")))
            sys.stderr.write("\nErrorcode/Error: %d - '%s'.\n" % (errcode, str(caughte)))
            sys.stderr.flush()
        raise MySQLdb.OperationalError(caughte)