code: def showall(self):
          
          p = _runshell([brctlexe, 'show'],
              "Could not show bridges.")
          wlist = map(str.split, p.stdout.read().splitlines()[1:])
          brwlist = filter(lambda x: len(x) != 1, wlist)
          brlist = map(lambda x: x[0], brwlist)
          return map(Bridge, brlist)
docs: Return a list of all available bridges.