code: def get_assets(self):
          '''
          Return a flat list of absolute paths to all assets required by this
          viewer
          '''
          return sum([
              [self.prefix_asset(viewer, relpath) for relpath in viewer.assets]
              for viewer in self.viewers
          ], []f get_assets(self):
          '''
          Return a flat list of absolute paths to all assets required by this
          viewer
          '''
          return sum([
              [self.prefix_asset(viewer, relpath) for relpath in viewer.assets]
              for viewer in self.viewers
          ], [])
docs: Return a flat list of absolute paths to all assets required by this
          viewer