How do you find out the caller function in JavaScript?

function main()
{
   Hello();
}

function Hello()
{
  // How do you find out the caller function is 'main'?
}

function Hello()
{
    alert("caller is " + arguments.callee.caller.toString());
}

function Hello() {
    alert("caller is " + arguments.callee.caller.toString());
}

function Hello() {
    alert("caller is " + Hello.caller.toString());
}

var Klass = function kls() {
   this.Hello = function() { alert(printStackTrace().join('nn')); };
}
new Klass().Hello();

arguments.callee.caller.name

arguments.callee.caller.toString();

arguments.callee.caller
arguments.callee.caller.caller
arguments.callee.caller.caller.caller

function Hello() {
    alert(Hello.caller);
}