ID:159707
 
var/list/L = list(T1 = list(), T2 = list())


I know you can have list inside of a list, but I wanna know how you would access, the list inside.

Ex: Getting list T1 in list L
The same way you would to a normal associative list? I don't know.

L[T1[associated_value]]
To make sure this is clear... note in your example code, T1 and T2 aren't new variable declarations or something. In order for that code to work they need to be vars (preferably containing distinct values) with those names, or they'll be invalid symbols.
As for getting the lists, it is like getting any other value, pretty much.
var/list/Lists = list( list("apple") , list("box") )

var/list/A = Lists[1] //get the list containing "apple"
var/list/B = Lists[2] //get the list containing "box"

for(var/list/L in Lists) //loop through all the lists in the list
src << "Found list (first item is [L[1]])"
//the embedded expression displays "apple" and "box"

var/list/associative = list("items" = list(1,2,3),"stuff" = list("a","b","c"))
var/list/C = associative["items"] //get the numbers list
var/list/D = associative["stuff"] //get the letters list