How to use the distlib.locators.logger.debug function in distlib

def _fetch(self, url, project_name, subvisit=False):
        locators.logger.debug('fetch(%s, %s)', url, project_name)
        versions = {}
        page = self.get_page(url)
        for link, rel in (page and page.links or []):
            # Let's instrospect one level down
            if self._should_queue(link, url, rel) and not subvisit:
                versions.update(self._fetch(link, project_name, subvisit=True))

            # Let's not see anything twice, I saw this check on distlib it
            # might be useful.
            if link not in self._seen:
                # Well, here we're ensuring that the first link of a given
                # version will be the one. Even if we find another package for
                # the same version, the first one will be used.
                version, distribution = self._visit_link(project_name, link)
                if version and version not in versions:
                    versions[version] = distribution

def _fetch(self, url, project_name, subvisit=False):
        locators.logger.debug('fetch(%s, %s)', url, project_name)
        versions = {}
        page = self.get_page(url)
        for link, rel in (page and page.links or []):
            # Let's instrospect one level down
            if self._should_queue(link, url, rel) and not subvisit:
                versions.update(self._fetch(link, project_name, subvisit=True))

            # Let's not see anything twice, I saw this check on distlib it
            # might be useful.
            if link not in self._seen:
                # Well, here we're ensuring that the first link of a given
                # version will be the one. Even if we find another package for
                # the same version, the first one will be used.
                version, distribution = self._visit_link(project_name, link)
                if version and version not in versions:
                    versions[version] = distribution

def _visit_link(self, project_name, link):
        self._seen.add(link)
        locators.logger.debug('_fetch() found link: %s', link)
        info = not self._is_platform_dependent(link) \
            and self.convert_url_to_download_info(link, project_name) \
            or None

        versions = {}
        if info:
            self._update_version_data(versions, info)
            return versions.items()[0]
        return None, None

def _visit_link(self, project_name, link):
        self._seen.add(link)
        locators.logger.debug('_fetch() found link: %s', link)
        info = not self._is_platform_dependent(link) \
            and self.convert_url_to_download_info(link, project_name) \
            or None

        versions = {}
        if info:
            self._update_version_data(versions, info)
            return list(versions.items())[0]
        return None, None