def getContext(self, key, default=None):
        """
        Retrieve the value for a key from the context.

        @param key: The key to look up in the context.

        @param default: The value to return if C{key} is not found in the
            context.

        @return: The value most recently remembered in the context for C{key}.
        """
        for ctx in reversed(self.contexts):
            try:
                return ctx[key]
            except KeyError:
                pass
        return default

        Retrieve the value for a key from the context.

        @param key: The key to look up in the context.

        @param default: The value to return if C{key} is not found in the
            context.

        @return: The value most recently remembered in the context for C{key}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/context.py