/home/thegtkjw/.trash/nextend-facebook-connect/providers/slack/slack.php
<?php

class NextendSocialProviderSlack extends NextendSocialProviderDummy {

    protected $color = '#4A154B';

    public function __construct() {
        $this->id     = 'slack';
        $this->docUrl = 'https://social-login.nextendweb.com/documentation/providers/slack/';
        $this->label  = 'Slack';
        $this->path   = dirname(__FILE__);
    }
}

NextendSocialLogin::addProvider(new NextendSocialProviderSlack());