POC of History API call implementation

1.) I don't get the naming "rpfx". Neither is "pfx" an English abbreviation, nor is it obvious what the "r" stands for.

2.) "DOTMKeys" is a suboptimal name. It doesn't contains any keys. It is about namespace prefixes of a key-value store.

Thinking about a good solution I'd draft something like

     ns = DOTMNamespace()
     print "Node namespace = " + ns.nodes

No "key" no "prefix" because handling the namespace shouldn't imply the implementation. The namespacing is just about separation.