function createCookie(name, value, days = false) {
    let expires = '';
    if (days !== false) {
      const date = new Date();
      date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
      expires = `; expires=${date.toGMTString()}`;
    }
    d.cookie = `${name}=${value}${expires}; path=/`;
  }

  function readCookie(name) {
    const nameEQ = `${name}=`;
    const ca = d.cookie.split(';');
    for (let i = 0; i < ca.length; i += 1) {
      let c = ca[i];
      while (c.charAt(0) === ' ') c = c.substring(1, c.length);
      if (c.indexOf(nameEQ) === 0) return c.substring(nameEQ.length, c.length);
    }
    return null;
  }

  function eraseCookie(name) {
    createCookie(name, '', -1);
  }