code: def p_Arg(p):
      '''
      Arg : Expression ThreeDotModifier
      '''
      if len(p) <= 2:
          p[0] = Arg(p[1], None)
      else:
          p[0] = Arg(p[1], p[2]f p_Arg(p):
      '''
      Arg : Expression ThreeDotModifier
      '''
      if len(p) <= 2:
          p[0] = Arg(p[1], None)
      else:
          p[0] = Arg(p[1], p[2])
docs: Arg : Expression ThreeDotModifier