code: def _index_loopbacks(self):
          
  
          self.loopbacks = {}
          try:
              result = _util.check_output_(['losetup', '-a'])
              for line in result.splitlines():
                  m = re.match(r'(.+): (.+) \((.+)\).*', line)
                  if m:
                      self.loopbacks[m.group(1)] = m.group(3)
          except Exception:
              pass
docs: Finds all loopbacks and stores them in :attr:`loopbacks`