/// <summary>
 /// Singleton
 /// </summary>
 /// <returns></returns>
 public static FormKNeighbours Instance()
 {
     if (instance == null)
     {
         instance = new FormKNeighbours();
     }
     return(instance);
 }
 /// <summary>
 /// cerrar el singleton, volvemos a poner la instancia a nula
 /// </summary>
 /// <param name="e"></param>
 protected override void OnClosed(EventArgs e)
 {
     instance = null;
 }