Issue trying to export query results to excel

Got this all set up, and works great!  But I am having an issue when I launch `zoql --excel` and enter a query.  I'm getting the following error: 

```
zoql>  select id from invoiceitem where InvoiceId = '******';
('Error: q', 'NameError("global name \'pd\' is not defined",)')
```
Appreciate any guidance on getting around this