package two

type stack struct {
	items []interface{}
}

func newStack() *stack {
	return &stack{}
}

func (s *stack) Push(element interface{}) interface{} {
	s.items = append(s.items, element)
	return element
}

func (s *stack) Pop() interface{} {
	l := len(s.items)
	element := s.items[l-1]
	s.items = s.items[:l-1]
	return element
}

func (s *stack) Peek() interface{} {
	return s.items[len(s.items)-1]
}

func (s *stack) Len() int {
	return len(s.items)
}

func (s *stack) IsEmpty() bool {
	return s.Len() == 0
}