code: def _filtered_walk(path, file_filter):
  		
  		for root, dirs, files in os.walk(path):
  			log.debug('looking in %s', root)
  			log.debug('files is %s', files)
  			file_filter.set_root(root)
  			files = filter(file_filter, files)
  			log.debug('filtered files is %s', files)
  			yield (root, dirs, files)
docs: static method that calls os.walk, but filters out
  		anything that doesn't match the filter