<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def set_pos(self, pos):
 """ set the position of this column in the Table """

        self.pos = pos
        if pos is not None and self.typ is not None:
            self.typ._v_pos = pos
        return self