<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_activations(self):
 """Return a list of activations."""

        res = (self.added, self.removed)

        self.added = set()
        self.removed = set()

        return res