from marionette_driver.marionette import Marionette # create a new Firefox instance client = Marionette() # navigate to page client.navigate("https://www.example.com") # wait until an element with id='my_element' is visible client.wait_until(lambda _: client.find_element("id", "my_element").is_displayed())In the above example, the wait_until function is used to wait until the element with id='my_element' is visible. The lambda function that is passed to the wait_until function takes the client as an argument and returns the result of the condition for which to wait. Package Library: marionette_driver.