class EncodeDemoTest < Test                      #inheritance in ruby  
      def setup(platform_info, logdir)
        @telnet_ip                  = platform_info["telnet_ip"]
        @telnet_login               = platform_info["telnet_login"]
        @telnet_password            = nil
        @filesys_path               = platform_info["filesys_path"]
        @host_files_path            = platform_info["host_files_path"]
        @host_machine_ip            = platform_info["host_machine_ip"]
        @linuxserver_ip             = platform_info["linuxserver_ip"]
        @target_prompt              = platform_info["target_prompt"]
        @demo_execuable_path        = platform_info["demo_execuable_path"]
        @mts4ea_machine_ip          = platform_info["mts4ea_machine_ip"]
        @mts4ea_files_path          = platform_info["mts4ea_files_path"]
        @ffmpeg_machine_ip          = platform_info["ffmpeg_machine_ip"]
        @ffmpeg_service_machine_ip  = platform_info["ffmpeg_service_machine_ip"]          
        @ffmpeg_files_path          = platform_info["ffmpeg_files_path"]
        @ffmpeg_login               = platform_info["ffmpeg_login"]
        @ffmpeg_password            = platform_info["ffmpeg_password"]
        @ffmpeg_prompt              = platform_info["ffmpeg_prompt"]
        @platform_info              = platform_info

could anyone tell me how argument passed in setup method .means what does that syntax means platform["telnet_ip"]