<?php
/**
 * This file is part of the Emperor Norton Commands.
 *
 * Public domain. All rites reversed.
 */

namespace EmperorNortonCommands\lib;

use DateTime;

/**
 * Class Holydays
 * @package EmperorNortonCommands\lib
 */
abstract class Holydays
{
    /**
     * Array of Holydays.
     *
     * Keys are composed of the Gregorian day and month (2 digits). Values are the
     * Holyday's name in the given language.
     *
     * @var mixed
     */
    protected $holydays = array();

    /**
     * Get Holyday.
     *
     * Returns the English name of the Holyday if there is a Holyday for given
     * the key, else returns empty string.
     *
     * @param string $key
     * @return string
     */
    public function getHolyday($key)
    {
        if (isset($key, $this->holydays)) {
            return $this->holydays[$key];
        }

        return '';
    }
}

<?php
/**
 * This file is part of the Emperor Norton Commands.
 *
 * Public domain. All rites reversed.
 */

namespace EmperorNortonCommands\lib;

use DateTime;

/**
 * Class Holydays
 * @package EmperorNortonCommands\lib
 */
abstract class Holydays
{
    /**
     * Array of Holydays.
     *
     * Keys are composed of the Gregorian day and month (2 digits). Values are the
     * Holyday's name in the given language.
     *
     * @var mixed
     */
    protected $holydays = array();

    /**
     * Get Holyday.
     *
     * Returns the name of the Holyday if there is a Holyday for given the key,
     * else returns empty string.
     *
     * @param string $key
     * @return string
     */
    public function getHolyday($key)
    {
        if (isset($this->holydays[$key])) {
            return $this->holydays[$key];
        }

        return '';
    }
}

Fix wrong usage of isset().
Fix wrong usage of isset().
