code: def format_options_error(self):
          
          allowed_keywords = self.allowed_keywords
          target = allowed_keywords.target
          matches = allowed_keywords.fuzzy_match(self.invalid_keyword)
          if not matches:
              matches = allowed_keywords.values
              similarity = 'Possible'
          else:
              similarity = 'Similar'
  
          loaded_backends = Store.loaded_backends()
          target = 'for {0}'.format(target) if target else ''
  
          if len(loaded_backends) == 1:
              loaded=' in loaded backend {0!r}'.format(loaded_backends[0])
          else:
              backend_list = ', '.join(['%r'% b for b in loaded_backends[:-1]])
              loaded=' in loaded backends {0} and {1!r}'.format(backend_list,
                                                              loaded_backends[-1])
  
          suggestion = ("If you believe this keyword is correct, please make sure "
                        "the backend has been imported or loaded with the "
                        "hv.extension.")
  
          group = '{0} option'.format(self.group_name) if self.group_name else 'keyword'
          msg=('Unexpected {group} {kw} {target}{loaded}.\n\n'
               '{similarity} keywords in the currently active '
               '{current_backend} renderer are: {matches}\n\n{suggestion}')
          return msg.format(kw="'%s'" % self.invalid_keyword,
                            target=target,
                            group=group,
                            loaded=loaded, similarity=similarity,
                            current_backend=repr(Store.current_backend),
                            matches=matches,
                            suggestion=suggestion)
docs: Return a fuzzy match message based on the OptionError