code: def acc(self):
      a = Vec(0, 0)
      for planet in self.gravSys.planets:
          if planet != self:
              v = planet.pos() - self.pos()
              a += (G * planet.m / abs(v) ** 3) * v
      return a
  
file_path: cpython/Lib/turtledemo/planet_and_moon.py
imports: from turtle import Shape, Turtle, mainloop, Vec2D
label_desc: Use image node_id 3 for calling the Star obj's underlying member method code with example usage: obj.acc() and returns: a