message: provide default value for cancellation token
diff: @@ -158,7 +158,7 @@ export const parseRule = (rule: string): Object => {
  /**
  * Debounces a function.
  */
  -export const debounce = (fn: () => any, wait: number = 0, immediate: boolean = false, token) => {
  +export const debounce = (fn: () => any, wait: number = 0, immediate: boolean = false, token = { cancelled: false }) => {
  if (wait === 0) {
  return fn;
  }
  