content: on a(k, x1, x2, x3, x4, x5)
  	script b
  		set k to k - 1
  		return a(k, b, x1, x2, x3, x4)
  	end script
  	if k ≤ 0 then
  		return (run x4) + (run x5)
  	else
  		return (run b)
  	end if
  end a
  
  on int(x)
  	script s
  		return x
  	end script
  	return s
  end int
  
  a(10, int(1), int(-1), int(-1), int(1), int(0))
  