pub fn abort(
  writer: Writer(a),
  reason reason: r,
) -> promise.Promise(Result(Nil, String))

pub fn close(
  writer: Writer(a),
) -> promise.Promise(Result(Nil, String))

pub fn closed(
  of writer: Writer(a),
) -> promise.Promise(Result(Nil, String))

pub fn desired_size(of writer: Writer(a)) -> Result(Int, Nil)

pub fn ready(
  of writer: Writer(a),
) -> promise.Promise(Result(Nil, String))

pub fn release_lock(
  writer: Writer(a),
) -> Result(Writer(a), String)

pub fn write(
  to writer: Writer(a),
  chunk chunk: a,
) -> promise.Promise(Result(Nil, String))