Operation op; //operation between sides (eg. sum, substration, etc.)

        //Constructor
        public NodeMatrBinary(Node_M L, Node_M R, Operation O)
        {
            left  = L;
            right = R;
            op    = O;
        }
 public NodeMatrUnary(Node_M R, Operation O)
 {
     right = R;
     op    = O;
 }