Iterates over all filters in the specified module/class.

def iter_filters_in(target):
    # type: (Any) -> Generator[Tuple[Text, Type[BaseFilter]]]
    """
    Iterates over all filters in the specified module/class.
    """
    global legacy_warned
    if not legacy_warned:
        # Set the global flag to ``True`` first, in case the user has
        # ``simplefilter('error')`` set.
        legacy_warned = True

        warn(
            'Legacy extension loader is deprecated and will be removed in '
                'Filters v1.4.  '
                'See http://filters.readthedocs.io/en/latest/extensions.html#legacy-extensions-loader '
                'for more information.',

            DeprecationWarning,
        )

    ift_result = is_filter_type(target)

    if ift_result is True:
        logger.debug(
            'Registering extension filter '
            '{cls.__module__}.{cls.__name__}.'.format(
                cls = target,
            ),
        )

        yield target.__name__, target
    elif is_module(target):
        for member_name, member in get_members(target):
            member_ift_result = is_filter_type(member)

            if member_ift_result is True:
                logger.debug(
                    'Registering extension filter '
                    '{cls.__module__}.{cls.__name__}.'.format(
                        cls = member,
                    ),
                )

                yield member.__name__, member
            else:
                logger.debug(
                    'Ignoring {module}.{name} ({reason})'.format(
                        module  = target.__name__,
                        name    = member_name,
                        reason  = member_ift_result,
                    ),
                )
    elif is_class(target):
        logger.debug(
            'Ignoring {cls.__module__}.{cls.__name__} ({reason}).'.format(
                cls     = target,
                reason  = ift_result,
            ),
        )
    else:
        logger.debug(
            'Ignoring {target!r} ({reason}).'.format(
                reason  = ift_result,
                target  = target,
            ),
        )