@Override
  public boolean validateOperator(
      final boolean showErrors, final HashSet<Operator> visited, final Object data) {
    if (this.succeedingOperators.size() < 2) {
      JOptionPane.showOptionDialog(
          this.panel.getVisualEditor(),
          "A multiinput operator must have at least two child!",
          "Error",
          JOptionPane.DEFAULT_OPTION,
          JOptionPane.ERROR_MESSAGE,
          null,
          null,
          null);

      return false;
    }

    for (final OperatorIDTuple<Operator> opIDT : this.succeedingOperators) {
      if (!opIDT.getOperator().validateOperator(showErrors, visited, data)) {
        return false;
      }
    }

    return true;
  }
  @Override
  public boolean variableInUse(final String variable, final HashSet<Operator> visited) {
    for (final OperatorIDTuple<Operator> opIDT : this.succeedingOperators)
      if (opIDT.getOperator().variableInUse(variable, visited)) return true;

    return false;
  }