func (ch *OverflowingChannel) overflowingDirect() {
	for elem := range ch.input {
		select {
		case ch.output <- elem:
		default:
		}
	}
	close(ch.output)
}
for entirely unbuffered cases
package channels
import "github.com/eapache/queue"
type OverflowingChannel struct {
	input, output chan interface{}
	length        chan int
	buffer        *queue.Queue
	size          BufferCap
}
func NewOverflowingChannel(size BufferCap) *OverflowingChannel {
	if size < 0 && size != Infinity {
		panic("channels: invalid negative size in NewOverflowingChannel")
	}
	ch := &OverflowingChannel{
		input:  make(chan interface{}),
		output: make(chan interface{}),
		length: make(chan int),
		size:   size,
	}
	if size == None {
		go ch.overflowingDirect()
	} else {
		ch.buffer = queue.New()
		go ch.overflowingBuffer()
	}
	return ch
}
func (ch *OverflowingChannel) In() chan<- interface{} {
	return ch.input
}
func (ch *OverflowingChannel) Out() <-chan interface{} {
	return ch.output
}
func (ch *OverflowingChannel) Len() int {
	if ch.size == None {
		return 0
	} else {
		return <-ch.length
	}
}
func (ch *OverflowingChannel) Cap() BufferCap {
	return ch.size
}
func (ch *OverflowingChannel) Close() {
	close(ch.input)
}