functionality to use different url if one fails and continue downloading

[mjishnu]

will it be possible to add functionality like using a different url only if one fails and continuing downloading #14 from where it left off, this will be usefull for downloading files which have exipre time so even after the link expires we can just use a new link and continue from where we left off. the current mirror function checks before hand if the 2nd url is valid even when the first one is vaild it would be great if it only checked the 2nd url in case the first one fails or returns an error

edit: found a way to do this, pypdl