addCallback = function (hook, callback) {

  const formattedHook = formatHookName(hook);

  if (!callback.name) {
    // eslint-disable-next-line no-console
    console.log(`// Warning! You are adding an unnamed callback to ${formattedHook}. Please use the function foo () {} syntax.`);
  }

  // if callback array doesn't exist yet, initialize it
  if (typeof Callbacks[formattedHook] === 'undefined') {
    Callbacks[formattedHook] = [];
  }

  Callbacks[formattedHook].push(callback);
}
@summary Add a callback function to a hook
@param {String} hook - The name of the hook
@param {Function} callback - The callback function