Binary Search Tree example in PHP

Node.php

<?php
/**
 * Created by PhpStorm.
 * User: jaredchu
 * Date: 31/08/2017
 * Time: 11:40
 */

class Node
{
    /**
     * @var Node
     */
    public $left;
    /**
     * @var integer
     */
    public $value;
    /**
     * @var Node
     */
    public $right;

    /**
     * Node constructor.
     * @param int $value
     */
    public function __construct($value)
    {
        $this->value = $value;
    }

    public function insert($value)
    {
        switch ($value <=> $this->value) {
            case -1:
                return $this->insertLeft($value);
            case 1:
                return $this->insertRight($value);
            default:
                return false;
        }
    }

    protected function insertLeft($value)
    {
        if ($this->left) {
            $this->left->insert($value);
        } else {
            $this->left = new Node($value);
        }

        return $this->left;
    }

    protected function insertRight($value)
    {
        if ($this->right) {
            $this->right->insert($value);
        } else {
            $this->right = new Node($value);
        }

        return $this->right;
    }

    protected function hasChild()
    {
        return !is_null($this->left) || !is_null($this->right);
    }
}