Test cases for twisted.logger._format.
| Function | nextLine | Retrive the file name and line number immediately after where this function is called. | 
| Class | STDLibLogObserverTests | Tests for STDLibLogObserver. | 
| Class | StdlibLoggingContainer | Continer for a test configuration of stdlib logging objects. | 
| Function | handlerAndBytesIO | Construct a 2-tuple of (StreamHandler, BytesIO)for testing
interaction with the 'logging' module. | 
| Class | BufferedHandler | A py_logging.Handlerthat remembers all logged records in a list. | 
Construct a 2-tuple of (StreamHandler, BytesIO) for testing
interaction with the 'logging' module.
| Returns | handler and io object (type: tuple of StreamHandlerandio.BytesIO) | |