math.combinatorics: minor cleanup to next-combination
math.combinatorics: minor cleanup to next-combination

factor/factor,factor/factor,mrjbq7/factor,tgunr/factor,factor/factor,mrjbq7/factor,tgunr/factor,mrjbq7/factor,tgunr/factor,tgunr/factor,factor/factor,factor/factor,mrjbq7/factor,mrjbq7/factor,tgunr/factor,tgunr/factor,mrjbq7/factor,factor/factor