@staticmethod
def set_update(keys, values):
    """
        Creates an update query to update a list of keys with a set of values.
        :param keys: a list of string keys or a single string key to update.
        :param values: a list of values or a single value to update. The values will be matched to keys by index.
        :return: a dictionary containing proper/valid update statement for MongoDB.
        """
    set_update = {'$set': {}}
    if isinstance(keys, str):
        set_update['$set'][keys] = values
    elif isinstance(keys, list):
        for index, key in enumerate(keys):
            set_update['$set'][key] = values[index]
    return set_update
