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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 make_abstract_dist(req):
 # type: (InstallRequirement) -> DistAbstraction """Factory to make an abstract dist object. Preconditions: Either an editable req with a source_dir, or satisfied_by or a wheel link, or a non-editable req with a source_dir. :return: A concrete DistAbstraction. """

    if req.editable:
        return IsSDist(req)
    elif req.link and req.link.is_wheel:
        return IsWheel(req)
    else:
        return IsSDist(req)