title: background function in Python
body: <p>I've got a Python script that sometimes displays images to the user. The images can, at times, be quite large, and they are reused often. Displaying them is not critical, but displaying the message associated with them is. I've got a function that downloads the image needed and saves it locally. Right now it's run inline with the code that displays a message to the user, but that can sometimes take over 10 seconds for non-local images. Is there a  way I could call this function when it's needed, but run it in the background while the code continues to execute? I would just use a default image until the correct one becomes available.</p>