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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _world_from_cwl(fn_name, fnargs, work_dir):
 """Reconstitute a bcbio world data object from flattened CWL-compatible inputs. Converts the flat CWL representation into a nested bcbio world dictionary. Handles single sample inputs (returning a single world object) and multi-sample runs (returning a list of individual samples to get processed together). """

    parallel = None
    output_cwl_keys = None
    runtime = {}
    out = []
    data = {}
    passed_keys = []
    for fnarg in fnargs:
        key, val = fnarg.split("=")
        # extra values pulling in nested indexes
        if key == "ignore":
            continue
        if key == "sentinel_parallel":
            parallel = val
            continue
        if key == "sentinel_runtime":
            runtime = dict(tz.partition(2, val.split(",")))
            continue
        if key == "sentinel_outputs":
            output_cwl_keys = _parse_output_keys(val)
            continue
        if key == "sentinel_inputs":
            input_order = collections.OrderedDict([x.split(":") for x in val.split(",")])
            continue
        else:
            assert key not in passed_keys, "Multiple keys should be handled via JSON records"
            passed_keys.append(key)
            key = key.split("__")
            data = _update_nested(key, _convert_value(val), data)
    if data:
        out.append(_finalize_cwl_in(data, work_dir, passed_keys, output_cwl_keys, runtime))

    # Read inputs from standard files instead of command line
    assert os.path.exists(os.path.join(work_dir, "cwl.inputs.json"))
    out, input_files = _read_from_cwlinput(os.path.join(work_dir, "cwl.inputs.json"), work_dir, runtime, parallel,
                                           input_order, output_cwl_keys)

    if parallel in ["single-parallel", "single-merge", "multi-parallel", "multi-combined", "multi-batch",
                    "batch-split", "batch-parallel", "batch-merge", "batch-single"]:
        out = [out]
    else:
        assert len(out) == 1, "%s\n%s" % (pprint.pformat(out), pprint.pformat(fnargs))
    return out, parallel, output_cwl_keys, input_files