def METHOD_NAME(self, commit=None):
    if not commit:
        commit = self.commit[0]
    refname = self.cref.get_name() + '/' + self.cref.get_arch() + '/' + self.cref.get_branch()
    print("Checking out %s" % commit)
    return subprocess.call(['flatpak', 'update', '--user', refname, '--commit', commit])