func NewMemoryDB() DB {
	return &memoryDB{
		countries: make(map[string]int),
	}
}
// NewMemoryDB returns a DB that stores the country visits in memory.
// If the database goes down, then all results are lost.
NewMemoryDB returns a DB that stores the country visits in memory.
If the database goes down, then all results are lost.
// NewMemoryDB returns a DB that stores the country visits in memory . // If the database goes down then all results are lost .
func NewMemoryDB() DB {
	return &memoryDB{
		countries: make(map[string]int),
	}
}
func NewMemoryDB ( ) DB { return & memoryDB { countries : make ( map [ string ] int ) , } }
NewMemoryDB returns a DB that stores the country visits in memory.
NewMemoryDB returns a DB that stores the country visits in memory .