public ConcreteCommandB(ReceieverB rB, ReceieverC rC)
 {
     this.receieverB = rB;
     this.receieverC = rC;
 }
 public ConcreteCommandA(ReceieverA rA, ReceieverC rC)
 {
     this.receieverA = rA;
     this.receieverC = rC;
 }