'Find a requested static file in an app\'s static locations.'

def find_in_app(self, app, path):

    storage = self.storages.get(app, None)
    if storage:
        if storage.prefix:
            prefix = ('%s%s' % (storage.prefix, os.sep))
            if (not path.startswith(prefix)):
                return None
            path = path[len(prefix):]
        if storage.exists(path):
            matched_path = storage.path(path)
            if matched_path:
                return matched_path
