Removing the warning message "on-variable type argument Int in type ... is unchecked" with Scala
<p>I have a function that calculate the tuple values only when the input is a tuple of four integers. </p>

<pre><code>def add(v:Any) = {
    if (v.isInstanceOf[(Int, Int, Int, Int)]) {
        val v2 = v.asInstanceOf[(Int, Int, Int, Int)]
        println(v2._1 + v2._2 + v2._3 + v2._4)
    } else {
        println("NOP")
    }
}

object Main extends App {
    add((1,1,1,1))
    add((1,2))
}

Main.main(args)
</code></pre>

<p>It's working, but I got a warning of "non-variable type argument ... is unchekced" warning. </p>

<pre><code>warning: non-variable type argument Int in type (Int, Int, Int, Int) is 
unchecked since it is eliminated by erasure
if (v.isInstanceOf[(Int, Int, Int, Int)]) {
</code></pre>

<p>Why this error, and what might be the best way to remove this warning message? </p>