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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 w(name, parallel, workflow, internal):
 """A workflow, allowing specification of sub-workflows for nested parallelization. name and parallel are documented under the Step (s) function. workflow -- a list of Step tuples defining the sub-workflow internal -- variables used in the sub-workflow but not exposed to subsequent steps """

    Workflow = collections.namedtuple("Workflow", "name parallel workflow internal")
    return Workflow(name, parallel, workflow, internal)