<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def parse_definitions(graph: BELGraph, enumerated_lines: Iterable[Tuple[int, str]], metadata_parser: MetadataParser, allow_failures: bool = False, use_tqdm: bool = False, tqdm_kwargs: Optional[Mapping[str, Any]] = None, ) -> None: """Parse the lines in the definitions section of a BEL script. :param graph: A BEL graph :param enumerated_lines: An enumerated iterable over the lines in the definitions section of a BEL script :param metadata_parser: A metadata parser :param allow_failures: If true, allows parser to continue past strange failures :param use_tqdm: Use :mod:`tqdm` to show a progress bar? :param tqdm_kwargs: Keywords to pass to ``tqdm`` :raises: pybel.parser.parse_exceptions.InconsistentDefinitionError :raises: pybel.resources.exc.ResourceError :raises: sqlalchemy.exc.OperationalError """

    parse_definitions_start_time = time.time()

    if use_tqdm:
        _tqdm_kwargs = dict(desc='Definitions', leave=False)
        if tqdm_kwargs:
            _tqdm_kwargs.update(tqdm_kwargs)
        enumerated_lines = tqdm(list(enumerated_lines), **_tqdm_kwargs)

    for line_number, line in enumerated_lines:
        try:
            metadata_parser.parseString(line, line_number=line_number)
        except (InconsistentDefinitionError, ResourceError) as e:
            parse_log.exception(LOG_FMT, line_number, 0, e.__class__.__name__, line)
            raise e
        except OperationalError as e:
            parse_log.warning('Need to upgrade database. See '
                              'http://pybel.readthedocs.io/en/latest/installation.html#upgrading')
            raise e
        except Exception as e:
            if not allow_failures:
                exc = MalformedMetadataException(line_number, line, 0)
                _log_parse_exception(graph, exc)
                raise exc from e

    graph.namespace_url.update(metadata_parser.namespace_url_dict)
    graph.namespace_pattern.update({
        keyword: pattern.pattern
        for keyword, pattern in metadata_parser.namespace_to_pattern.items()
    })

    graph.annotation_url.update(metadata_parser.annotation_url_dict)
    graph.annotation_pattern.update({
        keyword: pattern.pattern
        for keyword, pattern in metadata_parser.annotation_to_pattern.items()
    })
    graph.annotation_list.update(metadata_parser.annotation_to_local)
    graph.uncached_namespaces.update(metadata_parser.uncachable_namespaces)

    log.info('Finished parsing definitions section in %.02f seconds', time.time() - parse_definitions_start_time)