How to use the pkgcore.restrictions.packages.OrRestriction function in pkgcore

:return: :obj:`pkgcore.resolver.plan.merge_plan` instance
    """

    if nodeps:
        vdbs = list(map(misc.nodeps_repo, vdbs))
        dbs = list(map(misc.nodeps_repo, dbs))
    elif not verify_vdb:
        vdbs = list(map(misc.nodeps_repo, vdbs))
        dbs = list(dbs)

    if force_replace:
        resolver_cls = generate_replace_resolver_kls(resolver_cls)
    return resolver_cls(vdbs + dbs, plan.pkg_sort_highest,
                        plan.merge_plan.prefer_reuse_strategy, **kwds)

_vdb_restrict = packages.OrRestriction(
    packages.PackageRestriction("repo.livefs", values.EqualityMatch(False)),
    packages.AndRestriction(
        packages.PackageRestriction(
            "category", values.StrExactMatch("virtual")),
        packages.PackageRestriction(
            "package_is_real", values.EqualityMatch(False)),
        ),
    )


class empty_tree_merge_plan(plan.merge_plan):

    _vdb_restriction = _vdb_restrict

    def __init__(self, dbs, *args, **kwds):
        """

def masked(self):
        """Base package mask restriction."""
        return packages.OrRestriction(*self.pkg_masks)

def parse_description(value):
    """Value is used as a regexp matching description or longdescription."""
    matcher = values.StrRegex(value, case_sensitive=False)
    return packages.OrRestriction(*list(
        packages.PackageRestriction(attr, matcher)
        for attr in ('description', 'longdescription')))

if not repo.operations.supports("digests"):
        digest.error("no repository support for digests")

    for target in targets:
        if os.path.exists(target):
            try:
                restrictions.append(repo.path_restrict(target))
            except ValueError as e:
                digest.error(e)
        else:
            try:
                restrictions.append(parse_match(target))
            except ValueError:
                digest.error(f"invalid atom: {target!r}")

    restriction = packages.OrRestriction(*restrictions)
    namespace.restriction = restriction
    namespace.repo = repo

def pkg_upgrade(_value, namespace):
    pkgs = []
    for pkg in namespace.domain.all_installed_repos:
        matches = sorted(namespace.domain.all_source_repos.match(pkg.slotted_atom))
        if matches and matches[-1] != pkg:
            pkgs.append(matches[-1].versioned_atom)
    return packages.OrRestriction(*pkgs)

def generate_filter(masks, unmasks, *extra):
    # note that we ignore unmasking if masking isn't specified.
    # no point, mainly
    masking = make_mask_filter(masks, negate=True)
    unmasking = make_mask_filter(unmasks, negate=False)
    r = ()
    if masking:
        if unmasking:
            r = (packages.OrRestriction(masking, unmasking, disable_inst_caching=True),)
        else:
            r = (masking,)
    return packages.AndRestriction(disable_inst_caching=True, finalize=True, *(r + extra))

def parse_description(value):
    """Value is used as a regexp matching description or longdescription."""
    matcher = values.StrRegex(value, case_sensitive=False)
    return packages.OrRestriction(finalize=True, *list(
            packages.PackageRestriction(attr, matcher)
            for attr in ('description', 'longdescription')))

def downgrade_resolver(
        vdbs, dbs, verify_vdb=True, nodeps=False, force_replace=False,
        resolver_cls=plan.merge_plan, **kwds):
    """
    generate and configure a resolver for downgrading all processed nodes.

    :param vdbs: list of :obj:`pkgcore.repository.prototype.tree` instances
        that represents the livefs
    :param dbs: list of :obj:`pkgcore.repository.prototype.tree` instances
        representing sources of pkgs
    :param verify_vdb: should we stop resolving once we hit the vdb,
        or do full resolution?
    :return: :obj:`pkgcore.resolver.plan.merge_plan` instance
    """
    restrict = packages.OrRestriction(
        *list(atom(f'>={x.cpvstr}') for x in chain.from_iterable(vdbs)))
    f = partial(plan.merge_plan.prefer_downgrade_version_strategy, restrict)
    dbs = list(map(partial(misc.restrict_repo, restrict), dbs))
    # hack.
    if nodeps:
        vdbs = list(map(misc.nodeps_repo, vdbs))
        dbs = list(map(misc.nodeps_repo, dbs))
    elif not verify_vdb:
        vdbs = list(map(misc.nodeps_repo, vdbs))
        dbs = list(dbs)

    if force_replace:
        resolver_cls = generate_replace_resolver_kls(resolver_cls)
    return resolver_cls(dbs + vdbs, plan.pkg_sort_highest, f, **kwds)