Fork channel

Create a new channel as a copy of main.

Rename channel

Rename main to:

Delete channel

Delete main? This cannot be undone.

cocoa.m
// RUN: %clang -arch x86_64 %s -fsyntax-only -Xclang -print-stats
// REQUIRES: macos-sdk-10.12
#ifdef __APPLE__
#include <Cocoa/Cocoa.h>
#endif