anchor.diff:    replButton.click(() => {
       const node = $('<div>');
       const container = $('<div class="repl-box">');
  +
  +    let socket = null; //new SocketMonitor(socketUrl, terminal);
  +    const shutDown = () => {
  +      if (socket !== null) { socket.close(); }
  +      node.remove();
  +    };
  +
       node.append(container)
           .dialog({
                 width: 700,
  
positive.code:         }
      });
      const terminal = createTerminalIn(container[0]); // must be visible
      const socket = new SocketMonitor(socketUrl, terminal);
      const shutDown = () => { socket.close(); node.remove(); };
  
      destroyRepl(terminal)
        .then(() => createRepl(terminal));
        //.then(() => terminal.writeln('Ready...'));
    });
  
    // TODO: Call destroyRepl() when the page closes.
  
negative.code:   const replButton = $("#repl-button");
  
    cd.setupReplButton = (onOff) => {
      if (onOff === 'on' || true) {
        replButton.show();
      }
    };
  