docs: def check(self, feature):
      """ Loop through all our feature flag checkers and return true if any of them are true.
  
      The order of handlers matters - we will immediately return True if any handler returns true.
  
      If you want to a handler to return False and stop the chain, raise the StopCheckingFeatureFlags exception."""
      found = False
      for handler in self.handlers:
        try:
          if handler(feature):
             return True
        except StopCheckingFeatureFlags:
          return False
        except NoFeatureFlagFound:
          pass
        else:
          found = True
  
      if not found:
        message = u"No feature flag defined for {feature}".format(feature=feature)
        if current_app.debug and current_app.config.get(RAISE_ERROR_ON_MISSING_FEATURES, False):
          raise KeyError(message)
        else:
          log.info(message)
          missing_feature.send(self, feature=feature)
  
      return False