i am using a small php microframework and keep getting an error Uncaught Error: Undefined constant "mu" - class

Question

Fatal error: Uncaught Error: Undefined constant "mu" in E:\xampp\htdocs[[myphpframework]]\mu-clean\examples\hello1.php:3 Stack trace: #0 {main} thrown in E:\xampp\htdocs[[myphpframework]]\mu-clean\examples\hello1.php on line 3
the framework code:
<?php class µ{function __call($m,$a){$c=&$this->{$m.$a[0]};$c=$a[1]??(is_callable($c)?$c($this):$c);return isset($a[1])?
$this:$c;}function run(){foreach($this as$x=>$f)preg_match("#$x#i","$_SERVER[REQUEST_METHOD]$_SERVER[REQUEST_URI]",$p)&&
$f($this,$p);}function view($f,$d=[]){ob_start();extract($d);require"$this->cfgviews/$f.php";return ob_get_clean();}}#JL
the testing page code:
<?php
require(mu.php);
(new µ)
->get('/hello', function () {
echo "<p>Hello, world!</p>";
})
->run();
// Thank you, any assistance is highly appreciated.

Answer 1

In line 3 write:
require 'mu.php';
See docs ...