if (x != null && !(x instanceof ECFieldElement.F2m)) { throw new IllegalArgumentException("wrong field element passed"); }  if (y != null && !(y instanceof ECFieldElement.F2m)) { throw new IllegalArgumentException("wrong field element passed"); }   ECFieldElement.F2m.checkFieldElements(this.x, this.y);   ECFieldElement.F2m.checkFieldElements(this.x, this.curve.getA());
        protected F2m(ECCurve curve, ECFieldElement x, ECFieldElement y)        {            super(curve, x, y);        }