<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _get_last_tag(self):
 """ Gets the last release tag before self.current_tag """


        current_version = LooseVersion(
            self._get_version_from_tag(self.release_notes_generator.current_tag)
        )

        versions = []
        for tag in self.repo.tags():
            if not tag.name.startswith(self.github_info["prefix_prod"]):
                continue
            version = LooseVersion(self._get_version_from_tag(tag.name))
            if version >= current_version:
                continue
            versions.append(version)
        if versions:
            versions.sort()
            return "{}{}".format(self.github_info["prefix_prod"], versions[-1])