type Diff<
  T extends string,
  U extends string
> = (
  & { [P in T]: P }
  & { [P in U]: never }
  & { [x: string]: never }
)[T]

export type Omit<
  T,
  K extends keyof T
> = Pick<
  T,
  Diff<keyof T, K>
>

export type SingleOrArray<Properties, T extends keyof Properties> = {
  [P in T]: Properties[P] | Array<Properties[P]>
}