def fetch_export(username, req_id, filename)
      export_status_doc = export_status(username, req_id)
      if export_ready?(export_status_doc)
        download_export(export_status_doc, filename).each_with_index { |url, index| url.gsub!(/.*/, "#{filename}#{index}") }
      else
        nil
      end
    end
def fetch_export(username, req_id, filename)
      export_status_doc = export_status(username, req_id)
      if export_ready?(export_status_doc)
        download_export(export_status_doc, filename).each_with_index { |url, index| url.gsub!(/.*/, "#{filename}#{index}") }
      else
        nil
      end
    end
fetch_export downloads the mailbox export from Google.
 It takes a username, request id and a filename as
 arguments.  If the export consists of more than one file
 the file name will have numbers appended to indicate the
 piece of the export.

 fetch_export 'lholcomb2', 838382, 'lholcomb2'

 fetch_export reutrns nil in the event that the export is
 not yet ready.