code: def option_completer(cls, k,v):
          "Tab completion hook for the %%opts cell magic."
          line = v.text_until_cursor
          completions = cls.setup_completer()
          compositor_defs = {el.group:el.output_type.__name__
                             for el in Compositor.definitions if el.group}
          return cls.line_completer(line, completions, compositor_defsf option_completer(cls, k,v):
          "Tab completion hook for the %%opts cell magic."
          line = v.text_until_cursor
          completions = cls.setup_completer()
          compositor_defs = {el.group:el.output_type.__name__
                             for el in Compositor.definitions if el.group}
          return cls.line_completer(line, completions, compositor_defs)
docs: Tab completion hook for the %%opts cell magic.