5.0.0

• #42: The coroutine function now supports return in the passed generator
  function. This allows you to more generally return a value. This is a BC
  break as this is a feature that was only made possible with PHP 7, and
  before the coroutine function would only ever return the last thing that
  was yielded. If you depended on that feature, replace your last yield with
  a return.