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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 import_submodules(package_name, *submodules):
 """Import all submodules by package name."""

    package = sys.modules[package_name]
    return {
        name: importlib.import_module(package_name + '.' + name)
        for _, name, _ in pkgutil.walk_packages(package.__path__)
        if not submodules or name in submodules
    }