67                      ( '__lt__' , lambda  self , other: not  self  > =  other)]

68       }

69       roots =  set ( dir ( cls )) & set (convert)

70       if  not  roots:

71           raise  ValueError( 'must define at least one ordering operation: < > <= >=' )

72       root =  max (roots)       # prefer __lt__ to __le__ to __gt__ to __ge__

73       for  opname, opfunc in  convert[root]:

74           if  opname not  in  roots:

75               opfunc.__name__ =  opname

76               opfunc.__doc__ =  getattr ( int , opname).__doc__

77               setattr ( cls , opname, opfunc)

78       return  cls