Reads single document or list of documents from MongoDB collection
        :param cfg:
            {
                AccessParams.KEY_COLLECTION: <Collection to read data from>,
                AccessParams.KEY_MATCH_PARAMS: <A query that matches the documents to select>,
                AccessParams.KEY_TYPE: <AccessParams.TYPE_SINGLE or AccessParams.TYPE_MULTI>
            }
        :return: single document or list of documents

def get(self, cfg):
        """
        Reads single document or list of documents from MongoDB collection
        :param cfg:
            {
                AccessParams.KEY_COLLECTION: <Collection to read data from>,
                AccessParams.KEY_MATCH_PARAMS: <A query that matches the documents to select>,
                AccessParams.KEY_TYPE: <AccessParams.TYPE_SINGLE or AccessParams.TYPE_MULTI>
            }
        :return: single document or list of documents
        """
        collection = cfg[AccessParams.KEY_COLLECTION]
        match_params = cfg[AccessParams.KEY_MATCH_PARAMS] if AccessParams.KEY_MATCH_PARAMS in cfg else None

        target_type = cfg[AccessParams.KEY_TYPE] if AccessParams.KEY_TYPE in cfg else AccessParams.TYPE_MULTI
        if target_type == AccessParams.TYPE_SINGLE:
            result = CRUD.read_single(self.__db, collection, match_params)
        elif target_type == AccessParams.TYPE_MULTI:
            result = CRUD.read_multi(self.__db, collection, match_params)
        return result