Golang: Function to determine the arity of functions?

Is it possible to write a function to determine the arity of arbitrary functions, such that:

1.

func mult_by_2(x int) int {
      return 2 * x
}
fmt.Println(arity(mult_by_2)) //Prints 1

2.

func add(x int, y int) int {
      return x + y
}
fmt.Println(arity(add)) //Prints 2

3.

func add_3_ints(a, b, c int) int {
      return b + a + c
}
fmt.Println(arity(add_3_ints)) //Prints 3