<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _activate(self):
 """Activates the stream."""

        if six.callable(self.streamer):
            # If it's a function, create the stream.
            self.stream_ = self.streamer(*(self.args), **(self.kwargs))

        else:
            # If it's iterable, use it directly.
            self.stream_ = iter(self.streamer)