code: def get_string(self, key):
          
  
          # Massive hack, lol
          if key.startswith("lambda."):
              key = "lambda.items.{0}".format(key[7:])
          if key.startswith("apigateway."):
              key = "apigateway.items.{0}".format(key[11:])
  
          # Make sure key is in all_options
          if key not in self.all_options:
              kwargs = {}
              if len(self.chain) > 1:
                  kwargs['source'] = Meta(self.all_options, self.chain[-2]).source
              raise BadOptionFormat("Can't find key in options", key=key, chain=self.chain, **kwargs)
  
          return super(MergedOptionStringFormatter, self).get_string(key)
docs: Get a string from all_options