}
			done = true // Invalidate iterator
			race.Release(unsafe.Pointer(&racer))
		}()
		seq(yield)
		var v0 V
		v, ok = v0, false
		seqDone = true
	})
	next = func() (v1 V, ok1 bool) {
		race.Write(unsafe.Pointer(&racer)) // detect races

		if done {
			return
		}
		if yieldNext {
			panic("iter.Pull: next called again before yield")
		}
		yieldNext = true