How to use the cefpython3.cefpython.PostTask function in cefpython3

cef_browser = cef.CreateBrowserSync(window_info=window_info, url=real_url)
        browser = Browser(window, handle, cef_browser)

        bindings = cef.JavascriptBindings()
        bindings.SetObject('external', browser.js_bridge)
        bindings.SetFunction('alert', alert_func)

        cef_browser.SetJavascriptBindings(bindings)
        cef_browser.SetClientHandler(LoadHandler())

        instances[window.uid] = browser
        window.shown.set()

    window_info = cef.WindowInfo()
    window_info.SetAsChild(handle)
    cef.PostTask(cef.TID_UI, _create)

# Set WindowInfo object:
        # > windowInfo[0] = cefpython.WindowInfo()

        # On Windows there are keyboard problems in popups, when popup
        # is created using "window.open" or "target=blank". This issue
        # occurs only in wxPython. PyGTK or PyQt do not require this fix.
        # The solution is to create window explicitilly, and not depend
        # on CEF to create window internally.
        # If you set allowPopups=True then CEF will create popup window.
        # The wx.Frame cannot be created here, as this callback is
        # executed on the IO thread. Window should be created on the UI
        # thread. One solution is to call cefpython.CreateBrowser()
        # which runs asynchronously and can be called on any thread.
        # The other solution is to post a task on the UI thread, so
        # that cefpython.CreateBrowserSync() can be used.
        cefpython.PostTask(cefpython.TID_UI, self._CreatePopup, targetUrl)

        allowPopups = False
        return not allowPopups

def OnLoadError(self, browser, frame, error_code, failed_url, **_):
        """Called when the resource load for a navigation fails
        or is canceled."""
        if not frame.IsMain():
            # We are interested only in loading main url.
            # Ignore any errors during loading of other frames.
            return
        print("[screenshot.py] ERROR: Failed to load url: {url}"
              .format(url=failed_url))
        print("[screenshot.py] Error code: {code}"
              .format(code=error_code))
        # See comments in exit_app() why PostTask must be used
        cef.PostTask(cef.TID_UI, exit_app, browser)

cef_browser = cef.CreateBrowserSync(window_info=window_info, url=real_url)
        browser = Browser(window, handle, cef_browser)

        bindings = cef.JavascriptBindings()
        bindings.SetObject("external", browser.js_bridge)
        bindings.SetFunction("alert", alert_func)

        cef_browser.SetJavascriptBindings(bindings)
        cef_browser.SetClientHandler(LoadHandler())

        instances[window.uid] = browser
        window.shown.set()

    window_info = cef.WindowInfo()
    window_info.SetAsChild(handle)
    cef.PostTask(cef.TID_UI, _create)

# On Windows there are keyboard problems in popups, when popup
        # is created using "window.open" or "target=blank". This issue
        # occurs only in wxPython. PyGTK or PyQt do not require this fix.
        # The solution is to create window explicitly, and not depend
        # on CEF to create window internally. See Issue 80 for details:
        # https://code.google.com/p/cefpython/issues/detail?id=80

        # If you set allowPopups=True then CEF will create popup window.
        # The wx.Frame cannot be created here, as this callback is
        # executed on the IO thread. Window should be created on the UI
        # thread. One solution is to call cefpython.CreateBrowser()
        # which runs asynchronously and can be called on any thread.
        # The other solution is to post a task on the UI thread, so
        # that cefpython.CreateBrowserSync() can be used.
        cefpython.PostTask(cefpython.TID_UI, self._CreatePopup, targetUrl)

        allowPopups = False
        return not allowPopups

window_handle = create_window(title="PyWin32 example",
                                  class_name="pywin32.example",
                                  width=800,
                                  height=600,
                                  window_proc=window_proc,
                                  icon="resources/chromium.ico")
    
    window_info = cef.WindowInfo()
    window_info.SetAsChild(window_handle)
    
    if g_multi_threaded:
        # When using multi-threaded message loop, CEF's UI thread
        # is no more application's main thread. In such case browser
        # must be created using cef.PostTask function and CEF message
        # loop must not be run explicitilly.
        cef.PostTask(cef.TID_UI,
                     create_browser,
                     window_info,
                     {},
                     "https://www.google.com/")
        win32gui.PumpMessages()
        
    else:
        create_browser(window_info=window_info,
                       settings={},
                       url="https://www.google.com/")
        cef.MessageLoop()
    
    cef.Shutdown()