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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 objective_names(lang="en"):
 """This resource returns a list of the localized WvW objective names for the specified language. :param lang: The language to query the names for. :return: A dictionary mapping the objective Ids to the names. *Note that these are not the names displayed in the game, but rather the abstract type.* """

    params = {"lang": lang}
    cache_name = "objective_names.%(lang)s.json" % params
    data = get_cached("wvw/objective_names.json", cache_name, params=params)
    return dict([(objective["id"], objective["name"]) for objective in data])