should get(f, Nullable) be defined?

[KristofferC]

Moved from JuliaLang/julia#24528

I noted that my code include a fair bit of

maybe_res::Nullable = try_solve(...)
if isnull(res)
     # do some stuff
     # return some alternative
else
     get(maybe_res)
end

If `get(f, Nullable) was defined, like it is for dictionaries, then that would become

get(try_solve(...)) do
     # do some stuff
     # return some alternative
end

which is a bit nicer.