CWL target to retrieve a list of callable regions for parallelization.

def get_parallel_regions(batch):
    """CWL target to retrieve a list of callable regions for parallelization.
    """
    samples = [utils.to_single_data(d) for d in batch]
    regions = _get_parallel_regions(samples[0])
    return [{"region": "%s:%s-%s" % (c, s, e)} for c, s, e in regions]