What is wrong here? =(

<?php
//do not modify this file
class User {
    protected $name;
    protected $title;

    public function __construct($name = null, $title = null) {
        $this->name = $name;
        $this->title = $title;
    }

    public function __toString() {
        return $this->getSalutation();
    }

    public function getSalutation() {
        return $this->title . " " . $this->name;
    }

    public function getName() {
        return $this->name;
    }

    public function setName($name) {
        $this->name = $name;
    }

    public function getTitle() {
        return $this->title;
    }

    public function setTitle($title) {
        $this->title = $title;
    }
}

<?php

//add new child class here
class Developer extends User
{
  protected $skills = [];
  public functcion displayUserSkills() {
     return $this->name . " has the following skills:" . implode(", ", $this->getSkills());
  }

  public function getSkills() {
    return $this->skills;
  }

  public function setSkills($skill) {
        $this->skills = $skill;
  }
}