private void SaveButton_Click(object sender, EventArgs e)
        {
            SaveButton.Enabled = false;
            for (int i = 0; i < UsersLB.Items.Count; i++)
            {
                var user = UsersLB.Items[i] as Users;
                try
                {
                    var res = Model.Instance.client.SetUserCoach(user.Id, UsersLB.GetItemChecked(i));
                    if (!res)
                    {
                        errorLabel.Visible   = true;
                        SuccessLabel.Visible = false;
                        return;
                    }
                }
                catch (Exception ee)
                {
                    errorLabel.Visible   = true;
                    SuccessLabel.Visible = false;
                }
            }

            SaveButton.Enabled   = true;
            errorLabel.Visible   = false;
            SuccessLabel.Visible = true;
        }
        public MainForm()
        {
            InitializeComponent();
            var users = Model.Instance.client.GetAllUsers();

            foreach (var a in users)
            {
                UsersLB.Items.Add(a);
            }
            for (int i = 0; i < UsersLB.Items.Count; i++)
            {
                if ((UsersLB.Items[i] as Users).Right == 2)
                {
                    UsersLB.SetItemChecked(i, true);
                }
            }
        }