Similar to __pipe__, except that outpipe must be a Stream, in
		which case self.iterator will be modified in-place by calling
		outpipe.__call__ on it.

def extend(self, outpipe):
		"""Similar to __pipe__, except that outpipe must be a Stream, in
		which case self.iterator will be modified in-place by calling
		outpipe.__call__ on it.
		"""
		self.iterator = outpipe.__call__(self.iterator)
		return self