human
I wrote the below code

    if (((n * d) % 2) != 0):
        raise nx.NetworkXError('n    *    d    must    be    even')
    if (not (0 <= d < n)):
        raise nx.NetworkXError('the    0    <=    d    <    n    inequality    must    be    satisfied')
    if (d == 0):
        return empty_graph(n)
    if (seed is not None):
        random.seed(seed)
    def _suitable(edges, potential_edges):
        if (not potential_edges):
            return True
        for s1 in potential_edges:
            for s2 in potential_edges:
                if (s1 == s2):
                    break
                if (s1 > s2):
                    (s1, s2) = (s2, s1)
                if ((s1, s2) not in edges):
                    return True
        return False
    def _try_creation():
        edges = set()
        stubs = (list(range(n)) * d)
        while stubs:
            potential_edges = defaultdict((lambda : 0))
            random.shuffle(stubs)
            stubiter = iter(stubs)
            for (s1, s2) in zip(stubiter, stubiter):
                if (s1 > s2):
                    (s1, s2) = (s2, s1)
                if ((s1 != s2) and ((s1, s2) not in edges)):
                    edges.add((s1, s2))
                else:
                    potential_edges[s1] += 1
                    potential_edges[s2] += 1
            if (not _suitable(edges, potential_edges)):
                return None
            stubs = [node for (node, potential) in potential_edges.items() for _ in range(potential)]
        return edges
    edges = _try_creation()
    while (edges is None):
        edges = _try_creation()
    G = nx.Graph()
    G.add_edges_from(edges)
    return G

What's a good function header?
assistant
#Here's a good function header.

def random_regular_graph(d, n, seed=None):