code: def _get_zoom_level(zoom, process):
      
      if zoom is None:
          return reversed(process.config.zoom_levels)
      if isinstance(zoom, int):
          return [zoom]
      elif len(zoom) == 2:
          return reversed(range(min(zoom), max(zoom)+1))
      elif len(zoom) == 1:
          return zoom
docs: Determine zoom levels.