code: public static MemberCreator creator(final String pathServiceSid, 
                                          final String pathChannelSid, 
                                          final String identity) {
          return new MemberCreator(pathServiceSid, pathChannelSid, identity);
      }
docs: Create a MemberCreator to execute create.
  
  @param pathServiceSid The SID of the Service to create the resource under
  @param pathChannelSid The unique ID of the channel the new member belongs to
  @param identity The `identity` value that identifies the new resource's User
  @return MemberCreator capable of executing the create