code: func readCigarOps(cb []byte) []sam.CigarOp {
  	co := make([]sam.CigarOp, len(cb)/4)
  	for i := range co {
  		co[i] = sam.CigarOp(binary.LittleEndian.Uint32(cb[i*4 : (i+1)*4]))
  	}
  	return co
  }
docs: // len(cb) must be a multiple of 4.