updated doc strings.  added a some checking
updated doc strings.  added a some checking

huahbo/pyamg,huahbo/pyamg,kidaa/pyamg,kidaa/pyamg,kidaa/pyamg,pyamg/pyamg,pyamg/pyamg,huahbo/pyamg,pyamg/pyamg,kidaa/pyamg,huahbo/pyamg