human
Solve the following python programming problem given the following code:
@ contextlib.contextmanager 
def _assert_engines(self) : 
    'produce a mock series of engine calls.

        These are expected to match engine-related calls established
        by the test subject.

        ' 
    writer_conn = SingletonConnection () 
    writer_engine = SingletonEngine (writer_conn) 
    if self.slave_uri : 
        async_reader_conn = SingletonConnection () 
        async_reader_engine = SingletonEngine (async_reader_conn) 
else : 
        async_reader_conn = self 
        async_reader_engine = writer_engine 
if self.synchronous_reader : 
        reader_engine = async_reader_engine 
else : 
        reader_engine = writer_engine 
engines = AssertDataSource (writer_engine, reader_engine, async_reader_engine) 
    def create_engine(sql_connection, **kw) : 
        if (sql_connection == self.engine_uri) : 
            return engines.writer 
else : 
            if (sql_connection == self.slave_uri) : 
                return engines.async_reader 
else : 
                assert False 
engine_factory = mock.Mock (side_effect = create_engine) 
    engine_factory (sql_connection = self.engine_uri, ** dict (((k, mock.ANY) for k in self.factory._engine_cfg.keys ()))) 
    if self.slave_uri : 
        engine_factory (sql_connection = self.slave_uri, ** dict (((k, mock.ANY) for k in self.factory._engine_cfg.keys ()))) 
(yield AssertDataSource (writer_engine, reader_engine, async_reader_engine)) 
    self.assertEqual (engine_factory.mock_calls, self.create_engine.mock_calls) 
    for sym in [enginefacade._WRITER, enginefacade._READER, enginefacade._ASYNC_READER] : 
        self.assertEqual (engines.element_for_writer (sym).mock_calls, self.engines.element_for_writer (sym).mock_calls) 

    
    

    Fix the buggy line: async_reader_conn = self
assistant
#Here is Python program to fix the buggy line: async_reader_conn = self
.

async_reader_conn = writer_conn