std.json tree navigation help

[dennis]

I am having trouble understanding how to navigate the tree 
returned by std.json.  I am new to D programming, I have tried 
reading the std.json source code but I am still stumped.

I want to iterate the tree of JSONValue(s) by the json objects 
key names and I need to be test the type of the value pointed to 
by the key name so that I can descend into arrays or other 
objects as needed.  Basically I want search the JSONValue tree 
but I am stumped on how to do this.  Any examples or hints would 
be appreciated.