docs: def normalised(version):
      """Normalise a version string according to PEP 440, if possible."""
      norm_version = pkg_resources.parse_version(version)
      if not isinstance(norm_version, tuple):
          # Let setuptools (>= 8) do the normalisation
          return str(norm_version)
      else:
          # Homegrown normalisation for older setuptools (< 8)
          public, sep, local = version.lower().partition('+')
          # Remove leading 'v' from public version
          if len(public) >= 2:
              if public[0] == 'v' and public[1] in '0123456789':
                  public = public[1:]
          # Turn all chars except alphanumerics into periods in local version
          local = NON_ALPHANUMERIC.sub('.', local)
          return public + sep + local