Example of programmatically using session-state?

I have been looking at source code to try and figure out how to use session-state programmatically from a module. I see that src/main/radiusd.c allocates a state using fr_state_init but I don't see how to get at that? I see in the REQUEST there is a VALUE_PAIR that is a *state, but the session-state stuff looks like its from src/main/state.c and I would be looking for a state_entry_t or a state_t. So are there any examples of using session-state programmatically? TIA r