export type Pred<T, K> = (input: T) => K;
export type PredIndexed<T, K> = (
  input: T,
  index: number,
  array: readonly T[]
) => K;
export type PredIndexedOptional<T, K> = (
  input: T,
  index?: number,
  array?: readonly T[]
) => K;

/** types that may be returned by `keyof` */
export type Key = string | number | symbol;

/** Mapped type to remove optional, null, and undefined from all props */
export type NonNull<T> = { [K in keyof T]-?: Exclude<T[K], null | undefined> };

export type AnyArray<T> = ReadonlyArray<T> | Array<T>;