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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 sorted_tree(tree):
 """Sorts the dict representation of the tree The root packages as well as the intermediate packages are sorted in the alphabetical order of the package names. :param dict tree: the pkg dependency tree obtained by calling `construct_tree` function :returns: sorted tree :rtype: collections.OrderedDict """

    return OrderedDict(sorted([(k, sorted(v, key=attrgetter('key')))
                               for k, v in tree.items()],
                              key=lambda kv: kv[0].key))