static Employee[] Filter(Employee[] employees, string name = "", string surname1 = "", string surname2 = "", string nifContains = "")
        {
            // * Array.Resize modifies an array size
            List<Employee> filtro = new List<Employee>();
            foreach (Employee e in employees)
            {
                if (name != "" && e.name != null && e.name.ToLower().Equals(name.ToLower()))
                {
                    filtro.Add(e);
                }
                if (surname1 != "" && e.surname1 != null &&  e.surname1.ToLower().Equals(surname1.ToLower()))
                {
                    if (filtro.Contains(e))
                        continue;
                    else
                        filtro.Add(e);
                }
                if (surname2 != "" && e.surname2 != null && e.surname2.ToLower().Equals(surname2.ToLower()))
                {
                    if (filtro.Contains(e))
                        continue;
                    else
                        filtro.Add(e);
                }
                if (nifContains != "" && e.ID2 != null && e.ID2.ToLower().Contains(nifContains.ToLower()))
                {
                    if (filtro.Contains(e))
                        continue;
                    else
                        filtro.Add(e);
                }
            }
            return filtro.ToArray();
        }