1class application: 2 def __init__(self, environ, start_response): 3 self.environ = environ 4 self.start = start_response 5 6 def __iter__(self): 7 self.start('200', [(('!', '0'))]) 8 yield b'' 9 10 def close(self): 11 self.environ['wsgi.errors'].write('Close called.\n') 12 self.environ['wsgi.errors'].flush() 13