If you have to declare a list in a .baml file you can use this syntax:

1{
2 key1 [value1, value2, value3],
3 key2 [
4 value1,
5 value2,
6 value3
7 ]
8 key3 [
9 {
10 key1 value1,
11 key2 value2
12 },
13 {
14 key1 value1,
15 key2 value2
16 }
17 ]
18}
The commas are optional if doing a multiline list.