Deletes a download cache for recipes passed as arguments. If no
        argument is passed, it'll delete *all* downloaded caches. ::

            p4a clean_download_cache kivy,pyjnius

        This does *not* delete the build caches or final distributions.

def clean_download_cache(self, args):
        """ Deletes a download cache for recipes passed as arguments. If no
        argument is passed, it'll delete *all* downloaded caches. ::

            p4a clean_download_cache kivy,pyjnius

        This does *not* delete the build caches or final distributions.
        """
        ctx = self.ctx
        if hasattr(args, 'recipes') and args.recipes:
            for package in args.recipes:
                remove_path = join(ctx.packages_path, package)
                if exists(remove_path):
                    shutil.rmtree(remove_path)
                    info('Download cache removed for: "{}"'.format(package))
                else:
                    warning('No download cache found for "{}", skipping'.format(
                        package))
        else:
            if exists(ctx.packages_path):
                shutil.rmtree(ctx.packages_path)
                info('Download cache removed.')
            else:
                print('No cache found at "{}"'.format(ctx.packages_path))