code: func incCounter(c *[4]byte) {
  	if c[3]++; c[3] != 0 {
  		return
  	}
  	if c[2]++; c[2] != 0 {
  		return
  	}
  	if c[1]++; c[1] != 0 {
  		return
  	}
  	c[0]++
  }
docs: // incCounter increments a four byte, big-endian counter.