public async void Registration()
        {
            if (IsNullOrWhiteSpaceExtension.AllIsNullOrWhiteSpace(false, FirstName, SecondName, Address, BornDate, Mail, Number))
            {
                PharmacyService service = new PharmacyService();
                UserInfo        user    = await service.Add(usr);

                await Navigation.PopToRootAsync();
            }
        }
        public async void Registration()
        {
            if (IsNullOrWhiteSpaceExtension.AllIsNullOrWhiteSpace(false, FirstName, SecondName, Address, BornDate, Mail, Number))
            {
                PharmacyService service = new PharmacyService();
                var             user    = await service.Add(usr);

                if (user == null)
                {
                    Device.BeginInvokeOnMainThread(() =>
                    {
                        App.NavigationPage.Navigation.PopToRootAsync();
                    });
                }
                else
                {
                    Device.BeginInvokeOnMainThread(() =>
                    {
                        App.NavigationPage.Navigation.PopToRootAsync();
                        App.NavigationPage.Navigation.PushAsync(new LoginPage());
                    });
                }
            }
        }