'Check the downloaded archive against a checksum digest.
No-op if this stage checks code out of a repository.'

def check(self):

    if ((self.fetcher is not self.default_fetcher) and self.skip_checksum_for_mirror):
        tty.warn('Fetching    from    mirror    without    a    checksum!', 'This    package    is    normally    checked    out    from    a    version    control    system,    but    it    has    been    archived    on    a    spack    mirror.        This    means    we    cannot    know    a    checksum    for    the    tarball    in    advance.    Be    sure    that    your    connection    to    this    mirror    is    secure!')
    else:
        self.fetcher.check()
