@Override
  public @Nullable PsiExpression getExpression() {
    ASTNode exprChild = calcTreeElement().findChildByType(ElementType.EXPRESSION_BIT_SET);
    if (exprChild == null) return null;
    return (PsiExpression)SourceTreeToPsiMap.treeElementToPsi(exprChild);
  }
@Override
  public @Nullable PsiExpression getExpression()