docs: def get_local_version(sigdir, sig):
      """Get the local version of a signature"""
      version = None
      filename = os.path.join(sigdir, '%s.cvd' % sig)
      if os.path.exists(filename):
          cmd = ['sigtool', '-i', filename]
          sigtool = Popen(cmd, stdout=PIPE, stderr=PIPE)
          while True:
              line = sigtool.stdout.readline()
              if line and line.startswith('Version:'):
                  version = line.split()[1]
                  break
              if not line:
                  break
          sigtool.wait()
      return version