code: def getLVstats(self, *args):
          
          if not len(args) in (1, 2):
              raise TypeError("The getLVstats must be called with either "
                              "one or two arguments.")
          if self._vgTree is None:
              self._initDMinfo()
          if len(args) == 1:
              dmdev = self._mapLVname2dm.get(args[0])
          else:
              dmdev = self._mapLVtuple2dm.get(args)
          if dmdev is not None:
              return self.getDevStats(dmdev)
          else:
              return None
docs: Returns I/O stats for LV.
          
          @param args: Two calling conventions are implemented:
                       - Passing two parameters vg and lv.
                       - Passing only one parameter in 'vg-lv' format.  
          @return:     Dict of stats.