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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 active_thresholds_value_maps(keywords, exposure_key):
 """Helper to retrieve active value maps or thresholds for an exposure. :param keywords: Hazard layer keywords. :type keywords: dict :param exposure_key: The exposure key. :type exposure_key: str :returns: Active thresholds or value maps. :rtype: dict """

    if 'classification' in keywords:
        if keywords['layer_mode'] == layer_mode_continuous['key']:
            return keywords['thresholds']
        else:
            return keywords['value_map']
    if keywords['layer_mode'] == layer_mode_continuous['key']:
        classifications = keywords['thresholds'].get(exposure_key)
    else:
        classifications = keywords['value_maps'].get(exposure_key)
    if classifications is None:
        return None
    for value in list(classifications.values()):
        if value['active']:
            return value['classes']
    return None