Code/Php/func_abc.php

<?php
function func_c()
{
    echo "Function C\n";
    sleep(1);
}

function func_b()
{
    echo "Function B\n";
    sleep(1);
    func_c();
}

function func_a()
{
    echo "Function A\n";
    sleep(1);
    func_b();
}

func_a();
?>