PHP #2 Pipeline - Answer for https://www.testdome.com/questions/php/pipeline/20304?visibility=17&skillId=5

pipeline.php

<?php
class Pipeline
{
    public static function make_pipeline()
    { 
        $funcs = func_get_args(); 
        return function($arg) use ($funcs)
        { 
            foreach($funcs as $function) { 
                if(!isset($value))
                    $value = $function($arg); 
                else
                    $value = $function($value);
            } 
            return $value;
        };
    }
}

$fun = Pipeline::make_pipeline(
    function($x) { return $x * 3; }, 
    function($x) { return $x + 1; },
    function($x) { return $x / 2; });
echo $fun(3); # should print 5