python - Algorithm to unwrap recursive list of lists -

problem

say have list l of elements. elements can either literals (strings) and/or lists l', l'',... list l' can contain either literals and/or lists. unwrap them such list of literal combinations. combination looks easier show explain; refer following examples.

1. a basic example:

   l = [a,[b,c],d] 

   solution:

   s = [[a,b,d],[a,c,d]] 

   the solution combination of elements of l. second element list, wish create combination each element of list separately.

2. more advanced example:

   l = [ a, [b,c], [d,[e]] ] 

   solution:

   s = [ [a,b,d], [a,c,d], [a,b,e], [a,c,e] ] 

   i loop on elements each sublist create new combination. in third element (list [d,[e]]), second element yet list. contains 1 element e, when loop on it return 1 element.

3. complex example:

   l = [ [a,b], [ [c,d], [e,[f,g]] ] ] 

   solving subproblem, namely big list in second element:

   s' = [ [c,e,f], [c,e,g], [d,e,f], [d,e,g] ] 

   the partially solved problem becomes:

   l' = [ [a,b], [ [c,e,f], [c,e,g], [d,e,f], [d,e,g] ] ] 

   final solution becomes:

   s = [ [a,c,e,f], [a,c,e,g], [a,d,e,f], [a,d,e,g], [b,c,e,f], [b,c,e,g], [b,d,e,f], [b,d,e,g] ] 

   s' shows main problem solving can occur @ sublevel. need recursion.

question

i have big hunch there must existing algorithm kind of problem (or library; i'm using python 3). can point in right direction me? can't seem figure out myself.