code: func (bp *BytePool) Put(b []byte) {
  	if cap(b) < bp.w {
  		// someone tried to put back a too small buffer, discard it
  		return
  	}
  
  	select {
  	case bp.c <- b[:bp.w]:
  		// buffer went back into pool
  	default:
  		// buffer didn't go back into pool, just discard
  	}
  }
docs: // Put returns the given Buffer to the BytePool.