Flatten an array of arrays or map of arrays in Typescript single liner

flatten.ts

/**
 * Flatten a map of arrays or array of arrays to a single array
 * @param t
 */
export function flatten<T>(t: Array<Array<T>> | { [p: string]: Array<T> }): Array<T> {
  return Object.values(t).reduce((mem, val) => [...mem, ...val], [])
}