createMachine({
  context: { foo: 1 },
  entry: {
    type: "xstate.assign",
    exec: c => ({ foo: c.foo + 1 })
  }
})

createMachine({
  context: { foo: 1 },
  entry: assign(c => ({ foo: c.foo + 1 })) // c is unknown but should be { foo: number } instead
})

declare const createMachine: <C>(defintion: Machine<C>) => {}
type Machine<C> = {
  context: C,
  entry: {
    type: string,
    exec: (context: C) => unknown
  }
}

declare const assign: <C>(f: (context: C) => C) =>
  { type: "xstate.assign", exec: (context: C) => C }