export const activate = (context: vscode.ExtensionContext) => {
  let timer,
    counter = 1;

  let channel = vscode.window.createOutputChannel('Test Channel');
  vscode.commands.registerCommand('testExtension.clearChannel', () => channel.dispose());
  vscode.commands.registerCommand('testExtension.showChannel', () => channel.show() );
  vscode.commands.registerCommand('testExtension.hideChannel', () => channel.hide());
  vscode.commands.registerCommand('testExtension.startAppending', () => {
    if (!timer) {
      timer = setInterval(
        () => {
          if (counter % 2 === 0) {
            channel.appendLine(
              `${counter++} // Cancellation that controls whether or not we can cancel in the middle of type checking. In general cancelling is *not* safe for the type checker.  We might be in the middle of computing something, and we will leave our internals in an inconsistent state.  Callers who set the cancellation token should catch if a cancellation exception occurs, and should throw away and create a new TypeChecker.`
            )
          } else {
            counter++;
            channel.append(`Test\n`)
          }
        },

        1000
      );
    }
  });
};