CreateQuery concat_nested_test (children 3)
 Identifier concat_nested_test
 Columns definition (children 1)
  ExpressionList (children 1)
   ColumnDeclaration attrs (children 1)
    DataType Nested (children 1)
     ExpressionList (children 2)
      NameTypePair k (children 1)
       DataType String
      NameTypePair v (children 1)
       DataType String
 Storage definition (children 2)
  Function MergeTree
  Function tuple (children 1)
   ExpressionList