Function workflow

workflow<O, I = void, TState extends TypedState = UntypedState>(
    opts: WorkflowHandlerOpts<I, O>,
    fn: (ctx: WorkflowContext<TState>, input: I) => Promise<O>,
): I extends void
    ? (ctx: WorkflowContext) => Promise
    : (ctx: WorkflowContext<TState>, input: I) => Promise<O>

workflow<O, I = void, TState extends TypedState = UntypedState>(
    fn: (ctx: WorkflowContext<TState>, input: I) => Promise<O>,
): I extends void
    ? (ctx: WorkflowContext) => Promise
    : (ctx: WorkflowContext<TState>, input: I) => Promise<O>