code: def set_x(self, x):
          "Set x position"
          if(x>=0):
              self.x=x
          else:
              self.x=self.w+f set_x(self, x):
          "Set x position"
          if(x>=0):
              self.x=x
          else:
              self.x=self.w+x
docs: Set x position