Create a local mirror of one or more resources.

def fetch(opts):
    """
    Create a local mirror of one or more resources.
    """
    resources = _load(opts.resources, opts.output_dir)
    if opts.all:
        opts.resource_names = ALL
    reporthook = None if opts.quiet else lambda name: print('Fetching {}...'.format(name))
    if opts.verbose:
        backend.VERBOSE = True
    _fetch(resources, opts.resource_names, opts.mirror_url, opts.force, reporthook)
    return verify(opts)