message: [type] bem
diff: * b(['disabled', 'primary']) // 'button button--disabled button--primary'
  */
  +type Mod = string | { [key: string]: any };
  +type Mods = Mod | Mod[];
  +
  const ELEMENT = '__';
  const MODS = '--';
  -const join = (name: string, el: string, symbol: string) => (el ? name + symbol + el : name);
  +function join(name: string, el: string, symbol: string): string {
  + return el ? name + symbol + el : name;
  +}
  -const prefix = (name: string, mods: any): any => {
  +function prefix(name: string, mods: Mods): Mods {
  if (typeof mods === 'string') {
  return join(name, mods, MODS);
  }
  if (Array.isArray(mods)) {
  - return mods.map(item => prefix(name, item));
  + return mods.map(item => <Mod>prefix(name, item));
  }
  - const ret: { [key: string]: any } = {};
  + const ret: Mods = {};
  if (mods) {
  Object.keys(mods).forEach(key => {
  ret[name + MODS + key] = mods[key];
  @@ -29,9 +34,9 @@ const prefix = (name: string, mods: any): any => {
  }
  return ret;
  -};
  +}
  -export default (name: string) => (el: any, mods?: any) => {
  +export default (name: string) => (el: Mods, mods?: Mods): Mods => {
  if (el && typeof el !== 'string') {
  mods = el;
  el = '';
  