Update string, clone, Insert elements

Better IsEqual regarding map value updating

	// for every element of s
	for key, _ := range s {
		// check if it exists in the set "a"
		if _, exist := a[key]; !exist {
			return false
		}
		// if we consider its frequency
		// include
		// else if value1 != value2 {
		//	return false
	}