constructor(recvChannel) {
            this.channel = recvChannel;
            this.uuid = recvChannel.uuid;
            this.channel.addEventListener("message", ({data}) => this.handleMessage(data));
            this.messageHandlers = new Set();
        }
Handler for `RemoteGlobal <#RemoteGlobal>`_ commands.

This can't be constructed directly but must be obtained from
`global_channel() <#global_channel>`_ or
`start_global_channel() <#start_global_channel>`_.