A return type of job/iterable of jobs from a Job is interpreted as a replace

[vineetbansal]

Summary

When a creating dynamic flow, it is currently the Job's responsibility to create a Flow and return Response with a replace:

@job
def add_distributed(list_a):
    jobs = [add(val, 1) for val in list_a]
    flow = Flow(jobs)
    return Response(replace=flow)

This works fine, but we feel that a cleaner way might be if the following worked directly:

@job
def add_distributed(list_a):
    jobs = [add(val, 1) for val in list_a]
    return jobs

i.e. if a Job returns an iterable of Job objects (or a single Job object), it is interpreted as a replacement, and the actual mechanics of replacement (Response/replace) are handled internally in jobflow.

This enhancement is related to making jobflow closer to a drop-in replacement of a workflow engine (along with parsl, prefect etc) for the quacc platform.

This tweak allows this enhancement, while preserving old behavior.

Additional dependencies introduced (if any)

None

TODO (if any)

None

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