func (s *Set) Clear() {
	s.m = make(map[string]struct{})
}
Clear removes all items from the Set.
package strset
import (
	"fmt"
	"strings"
)
var (
	keyExists   = struct{}{}
	nonExistent string
)
const maxInt = int(^uint(0) >> 1)
type Set struct {
	m map[string]struct{}
}
func New(ts ...string) *Set {
	s := NewWithSize(len(ts))
	s.Add(ts...)
	return s
}
func NewWithSize(size int) *Set {
	return &Set{make(map[string]struct{}, size)}
}
func (s *Set) Add(items ...string) {
	for _, item := range items {
		s.m[item] = keyExists
	}
}
func (s *Set) Remove(items ...string) {
	for _, item := range items {
		delete(s.m, item)
	}
}
func (s *Set) Pop() string {
	for item := range s.m {
		delete(s.m, item)
		return item
	}
	return nonExistent
}
func (s *Set) Pop2() (string, bool) {
	for item := range s.m {
		delete(s.m, item)
		return item, true
	}
	return nonExistent, false
}
func (s *Set) Has(items ...string) bool {
	has := false
	for _, item := range items {
		if _, has = s.m[item]; !has {
			break
		}
	}
	return has
}
func (s *Set) HasAny(items ...string) bool {
	has := false
	for _, item := range items {
		if _, has = s.m[item]; has {
			break
		}
	}
	return has
}
func (s *Set) Size() int {
	return len(s.m)
}