// AddTown <townName> <countryName>
public string Execute(string[] data)
{
if (!userSessionService.IsLoggedIn())
{
throw new InvalidOperationException("Invalid credentials!");
}
string townName = data[0];
string country = data[1];
var townExists = townService.Exists(townName);
if (townExists)
{
throw new ArgumentException($"Town {townName} was already added!");
}
var townDto = new TownDto()
{
TownName = townName, CountryName = country
};
var town = townService.Add(townName, country);
return($"Town {townName} was added successfully!");
}