code: def mate_bottom(self):
          " connect to the bottom of the cup"
          return Mate(self, CoordSystem(\
              origin=(0, 0, -self.height),\
              xDir=(1, 0, 0),\
              normal=(0, 0, 1))f mate_bottom(self):
          " connect to the bottom of the cup"
          return Mate(self, CoordSystem(\
              origin=(0, 0, -self.height),\
              xDir=(1, 0, 0),\
              normal=(0, 0, 1)))
docs: connect to the bottom of the cup