public bool Authenticate(string username, string password = null)
{
var userResponse = _connection.AuthInfoUser(username);
if (userResponse.Code == 281)
{
return(true);
}
if (userResponse.Code != 381 || password == null)
{
return(false);
}
var passResponse = _connection.AuthInfoPass(password);
return(passResponse.Code == 281);
}