val id = java.util.UUID.randomUUID().toString
kernel.publish.html("Waiting", id)
kernel.comm.receiver("A") { data =>
kernel.publish.updateHtml(s"<code>$data</code>", id)
}
{"content":"foo"}
id: String = "084d2e09-d38a-4d7a-b256-cba3408d31c5"
kernel.publish.js("""
// runs in the front-end (browser)
var comm = Jupyter.notebook.kernel.comm_manager.new_comm("A", {"a": 2, "b": false});
var message = prompt("Message")
comm.send({"content": message});
""")