Lexically nested functions within enclosing function

lexical_sum.js

// Lexically nested function definitions defined within enclosing function 
function Sum(arg0) {
  function Inner1(arg1) {
    function Inner2(arg2) {
      return arg0 + arg1 + arg2;
    }
    return Inner2;
  }
  return Inner1;
}
console.log(Sum(3)(4)(5));