How to create nogc code?

[Adam Sansier via Digitalmars-d-learn]

Also, When dealing with a complex tree like structure, is there 
an easy way to recursively free it by free'ing all the sub 
elements?

Also, since I'm dealing with simple structs and strings, maybe I 
more intelligent string type can be used? One that uses opAssign 
to do reference counting? I imagine that the only time there are 
issues is during assignment, in most cases?