CreateQuery test_null (children 3)
 Identifier test_null
 Columns definition (children 1)
  ExpressionList (children 1)
   ColumnDeclaration a (children 1)
    DataType Array (children 1)
     ExpressionList (children 1)
      DataType Nullable (children 1)
       ExpressionList (children 1)
        DataType Int64
 Storage definition (children 3)
  Function MergeTree
  Identifier a
  Set
