def toposort_flatten(data, sort=True):

    result = []
    for d in toposort(data):
        try:
            result.extend((sorted if sort else list)(d))
        except TypeError as e:
            result.extend(list(d))
    return result
Returns a single list of dependencies. For any set returned by
dataset/ETHPy150Open Brobin/django-seed/django_seed/toposort.py/toposort_flatten