docs: def get(self, name, default=None):
          """
          Returns an extension instance with a given name.
  
          In case there are few extensions with a given name, the first one
          will be returned. If no extensions with a given name are exist,
          the `default` value will be returned.
  
          :param name: (str) an extension name
          :param default: (object) a fallback value
          :returns: (object) an extension instance
          """
          try:
              value = self[name]
          except KeyError:
              value = default
          return value