function loop () {
  for (var i = 0; i < 100; i++) {
    assert.equal(Math.abs(-i), func(-i))
  }
  (typeof setImmediate != 'undefined' ? setImmediate : process.nextTick)(loop)
}
This example creates an ffi.Callback from the "Math.abs()" JavaScript function
then creates a ffi.ForeignFunction from that callback function pointer.

The result is basically the same as calling "Math.abs()" directly, haha!

This example should basically just run forever, in an endless loop.
This file is a "pummel test" of sorts for:
    https://github.com/rbranson/node-ffi/issues/74

We should run this file periodically for a period of ~10 minutes to make sure
it doesn't crash ever.