packages/mesh/lib/streams/std/writable-stream.js
function IsWritableStreamDefaultWriter(x) {
  if (!typeIsObject(x)) {
    return false;
  }

  if (!Object.prototype.hasOwnProperty.call(x, '_ownerWritableStream')) {
    return false;
  }

  return true;
}
function IsWritableStreamDefaultWriter(x) {
  if (!typeIsObject(x)) {
    return false;
  }

  if (!Object.prototype.hasOwnProperty.call(x, '_ownerWritableStream')) {
    return false;
  }

  return true;
}
Abstract operations for the WritableStreamDefaultWriter.