text: import attr
  
  
  @attr.s
  class RTCConfiguration:
      """
      The :class:`RTCConfiguration` dictionary is used to provide configuration
      options for an :class:`RTCPeerConnection`.
      """
      iceServers = attr.ib(default=None)
      "A list of :class:`RTCIceServer` objects to configure STUN / TURN servers."
  
  
  @attr.s
  class RTCIceServer:
      """
      The :class:`RTCIceServer` dictionary defines how to connect to a single
      STUN or TURN server. It includes both the URL and the necessary credentials,
      if any, to connect to the server.
      """
      urls = attr.ib()
      """
      This required property is either a single string or a list of strings,
      each specifying a URL which can be used to connect to the server.
      """
      username = attr.ib(default=None)
      "The username to use during authentication (for TURN only)."
      credential = attr.ib(default=None)
      "The credential to use during authentication (for TURN only)."
      credentialType = attr.ib(default='password')
  