provide a decent default for download_fu
provide a decent default for download_fu

in case someone wants to use it without our client classes

geometalab/drf-utm-zone-info,geometalab/osmaxx,geometalab/drf-utm-zone-info,geometalab/osmaxx,geometalab/osmaxx-frontend,geometalab/osmaxx-frontend,geometalab/osmaxx,geometalab/osmaxx-frontend,geometalab/osmaxx-frontend,geometalab/osmaxx