sage: DiGraph({0: [1]}, immutable=False).neighbors(1)
[0]
sage: DiGraph({0: [1]}, immutable=True).neighbors(1)
[]The ticket is https://trac.sagemath.org/ticket/25550 and I am not planning to work on it at least for now.
-- Jori Mäntysalo
Maybe this should be mentioned in the list, as this is quite a basic
function:
