private void _savePositions(string[] positions)
 {
     if (positions.Count() == 0)
         throw new Exception("Employee must have at least one position");
     Users_Team.Items.RemoveAll(items => items.User == SelectedEmployee.User);
     for (int i = 0; i < positions.Count(); i++)
     {
         Users_Team ut = new Users_Team()
         {
             IsLeader = false,
             Position = Position.Items.Where(item => item.Name == positions[i]).FirstOrDefault(),
             Team = CurrentTeam.Team,
             User = SelectedEmployee.User
         };
         Users_Team.Items.Add(ut);
     }
 }
 public User_TeamVM(Users_Team userTeam)
 {
     _userTeam = userTeam;
 }