def middle_click(self, x, y, n=<NUM_LIT:1>, pre_dl=None, post_dl=None):
self.delay(pre_dl)<EOL>self.m.click(x, y, <NUM_LIT:3>, n)<EOL>self.delay(post_dl)<EOL>
Middle click at ``(x, y)`` on screen for ``n`` times.
        at begin.

        **中文文档**

        在屏幕的 ``(x, y)`` 坐标处中键单击 ``n`` 次。