pub fn close(port: MessagePort) -> Nil

pub fn on_message(
  port: MessagePort,
  run handler: fn(message_event.MessageEvent) -> a,
) -> Nil

pub fn on_message_error(
  port: MessagePort,
  run handler: fn(message_event.MessageEvent) -> a,
) -> Nil

pub fn post_message(
  to port: MessagePort,
  data data: a,
) -> Result(Nil, String)

pub fn start(port: MessagePort) -> Nil