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

def mate_top(self):
        " top of the stator"
        return Mate(self, CoordSystem(
            origin=(0, 0, self.length/2),
            xDir=(0, 1, 0),
            normal=(0, 0, 1)
            ))