<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:

def teardown(self):
        '''
        Clean up all expectations and restore the original attribute of the
        mocked object.
        '''
        if not self._torn:
            self._expectations = []
            self._torn = True
            self._teardown()