def __init__(self, d):
        """
        Create the deferred that will be fired at the end, and initialize
        data structures.
        """
        self.deferred = d
        self.outData = []
        self.errData = []

        Create the deferred that will be fired at the end, and initialize
        data structures.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_process.py