CreateQuery test_table (children 3)
 Identifier test_table
 Columns definition (children 1)
  ExpressionList (children 3)
   ColumnDeclaration b (children 1)
    DataType Int64
   ColumnDeclaration a (children 1)
    DataType Int64
   ColumnDeclaration grp_aggreg (children 1)
    DataType AggregateFunction (children 1)
     ExpressionList (children 2)
      Identifier groupArrayArray
      DataType Array (children 1)
       ExpressionList (children 1)
        DataType UInt64
 Storage definition (children 2)
  Function MergeTree (children 1)
   ExpressionList
  Identifier a
