code: func (s *stack) String() string {
  	var result string
  	for _, stack := range s.stk {
  		if len(stack) == 0 {
  			result += "00000000  <empty>\n"
  		}
  		result += hex.Dump(stack)
  	}
  
  	return result
  }
docs: // String returns the stack in a readable format.