/** Opération binaire, Exp  char Exp. */
public class ExpOpBin extends Exp {
  public Exp e1, e2;
  public char op;
  public ExpOpBin(Exp e1, char op, Exp e2) {
    super(e1, e2); this.e1 = e1; this.op = op; this.e2 = e2;
  }
  public String toString() { return super.toString() + "(" + op + ")"; }
}