code: function normalize(obj, caseType = 'camel') {
    let ret = obj;
    const method = methods[caseType];
  
    if (Array.isArray(obj)) {
      ret = [];
      let i = 0;
  
      while (i < obj.length) {
        ret.push(normalize(obj[i], caseType));
        ++i;
      }
    } else if (isPlainObject(obj)) {
      ret = {};
      // eslint-disable-next-line guard-for-in, no-restricted-syntax
      for (const k in obj) {
        ret[method(k)] = normalize(obj[k], caseType);
      }
    }
  
    return ret;
  }
docs: Normalize all keys of `obj` recursively.
  @param {Object} obj to normalize
  @param {String} caseType type of case to convert object to
  @return {Object}
  @api public