docs: def sandbox(verbose, app):
      """Deploy app using Heroku to the MTurk Sandbox."""
      # Load psiTurk configuration.
      config = PsiturkConfig()
      config.load_config()
  
      # Set the mode.
      config.set("Experiment Configuration", "mode", "sandbox")
      config.set("Server Parameters", "logfile", "-")
  
      # Ensure that psiTurk is in sandbox mode.
      config.set("Shell Parameters", "launch_in_sandbox_mode", "true")
  
      # Do shared setup.
      deploy_sandbox_shared_setup(verbose=verbose, app=app)