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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 _versions_from_changelog(changelog):
 """ Return all released versions from given ``changelog``, sorted. :param dict changelog: A changelog dict as returned by ``releases.util.parse_changelog``. :returns: A sorted list of `semantic_version.Version` objects. """

    versions = [Version(x) for x in changelog if BUGFIX_RELEASE_RE.match(x)]
    return sorted(versions)