code: def trim_filter(filter, levels=1):
      '''Trim @ref levels levels from the front of each path in @filter.'''
      trimmed = [f[levels:] for f in filter]
      return [f for f in trimmed if ff trim_filter(filter, levels=1):
      '''Trim @ref levels levels from the front of each path in @filter.'''
      trimmed = [f[levels:] for f in filter]
      return [f for f in trimmed if f]
docs: Trim @ref levels levels from the front of each path in @filter.