Program at 1:0
+-- sourceType: script
+-- body:
|   +-- 0: ExpressionStatement at 1:0
|   |   +-- expression: SequenceExpression at 1:0
|   |   |   +-- expressions:
|   |   |   |   +-- 0: ArrayExpression at 1:0
|   |   |   |   |   +-- elements:
|   |   |   |   |   |   +-- 0: SpreadElement at 1:1
|   |   |   |   |   |   |   +-- argument: Identifier at 1:4
|   |   |   |   |   |   |   |   +-- name: a
|   |   |   |   |   |   +-- 1: Identifier at 1:7
|   |   |   |   |   |   |   +-- name: b