human
I wrote the below code

    if (dependencies is None):
        dependencies = {k: get_dependencies(dsk, k) for k in dsk}
    dependents = reverse_dict(dependencies)
    ndeps = ndependents(dependencies, dependents)
    maxes = child_max(dependencies, dependents, ndeps)
    def key(x):
        return ((- maxes.get(x, 0)), str(x))
    return dfs(dependencies, dependents, key=key)

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

def order(dsk, dependencies=None):