filterTags not returning

[pnorman]

If filterTags does not include a return statement, ogr2osm blows up

Traceback (most recent call last):
  File "./ogr2osm.py", line 570, in <module>
    output()
  File "./ogr2osm.py", line 528, in output
    for (key, value) in featuresmap[node].tags.items():
AttributeError: 'NoneType' object has no attribute 'items'