def open_url(self, url):
return self.http.post('<STR_LIT:url>', {'<STR_LIT:url>': url})<EOL>
TODO: Never successed using before.
https://github.com/facebook/WebDriverAgent/blob/master/WebDriverAgentLib/Commands/FBSessionCommands.m#L43
Args:
    url (str): url

Raises:
    WDAError