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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 make_db_data_fetcher(postgresql_conn_info, template_path, reload_templates, query_cfg, io_pool):
 """ Returns an object which is callable with the zoom and unpadded bounds and which returns a list of rows. """


    sources = parse_source_data(query_cfg)
    queries_generator = make_queries_generator(
        sources, template_path, reload_templates)
    return DataFetcher(
        postgresql_conn_info, queries_generator, io_pool)