availDisk :: Node -> Int
availDisk t =
  let _f = fDsk t
      _l = loDsk t
  in if _f < _l
       then 0
       else _f - _l
availDisk :: Node -> Int
availDisk t =
  let _f = fDsk t
      _l = loDsk t
  in if _f < _l
       then 0
       else _f - _l
availDisk t =
  let _f = fDsk t
      _l = loDsk t
  in if _f < _l
       then 0
       else _f - _l