<?php

class Demo {
    public function run(?string $maybe, string $part): string
    { 
       $address = $maybe;
       $address .= $address ? ' - ' . $part : $part;

       return $address;
    }
    
    function a(): void {
        echo "maybe - part";
        echo $this->run('maybe', 'part');
    }
    
    
    function b(): void {
        echo "part";
        echo $this->run(null, 'part');
    }
}