raise exception_class(message, screen, stacktrace)

I got this error message when trying posting.

```
Traceback (most recent call last):
File "fbposter.py", line 87, in
main()
File "fbposter.py", line 61, in main
addMediaButton.click()
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/selenium/webdriver/remote/webelement.py", line 80, in click
self._execute(Command.CLICK_ELEMENT)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/selenium/webdriver/remote/webelement.py", line 633, in _execute
return self._parent.execute(command, params)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/selenium/webdriver/remote/webdriver.py", line 321, in execute
self.error_handler.check_response(response)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/selenium/webdriver/remote/errorhandler.py", line 242, in check_response
raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.WebDriverException: Message: unknown error: Element ... is not clickable at point (473, 458). Other element would receive the click:

(Session info: chrome=69.0.3497.100)
(Driver info: chromedriver=2.42.591059 (a3d9684d10d61aa0c45f6723b327283be1ebaad8),platform=Mac OS X 10.13.6 x86_64)
```

Please advice. Thank you.