initial tree topology

this may not compile, I just send this out so that you guys know what to expect. I am working the test code right now. This is my second time using go, so...
1. put this test struct into function locally.
2. Instead of defining type _testInfo_, use
```
[]struct{
  int unit64
  ... 
}{
  {uint64(0), ...}
   ...
}
```