sequences.extras: cleanup change-last{-unsafe}
sequences.extras: cleanup change-last{-unsafe}

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