How to use the johnnydep.lib.OrderedDefaultListDict function in johnnydep

def flatten_deps(johnnydist):
    # TODO: add the check for infinite recursion in here (traverse parents)
    johnnydist.log.debug("resolving dep tree")
    dist_map = OrderedDefaultListDict()
    spec_map = defaultdict(str)
    extra_map = defaultdict(set)
    required_by_map = defaultdict(list)
    for dep in anytree.iterators.LevelOrderIter(johnnydist):
        dist_map[dep.name].append(dep)
        spec_map[dep.name] = dep.req.specifier & spec_map[dep.name]
        extra_map[dep.name] |= set(dep.extras_requested)
        required_by_map[dep.name] += dep.required_by
    for name, dists in dist_map.items():
        spec = spec_map[name]
        spec.prereleases = True
        extras = extra_map[name]
        required_by = list(OrderedDict.fromkeys(required_by_map[name]))  # order preserving de-dupe
        for dist in dists:
            if dist.version_latest_in_spec in spec and set(dist.extras_requested) >= extras:
                dist.required_by = required_by