[bug] Dependencies are not recognised in dictionaries

[jan-janssen]

Ideally they should be recognized in any datatype that supports iteration.

[jan-janssen]

At least lists work:

from executorlib import Executor

with Executor(backend="local") as exe:
    fs = exe.submit(sum, [exe.submit(sum, [i, i]) for i in range(3)])
    print(fs.result())