func (s *Stack) Push(element interface{}) {
	s.len++
	s.data = append(s.data, element)
}
Push adds an element to stack
package stack
import (
	"errors"
)
type Stack struct {
	data []interface{}
	len  int
}
func New() *Stack {
	return &Stack{}
}
func (s *Stack) Length() int {
	return s.len
}
func (s *Stack) IsEmpty() bool {
	return s.len == 0
}
func (s *Stack) Peek() interface{} {
	return s.data[s.len-1]
}