CreateQuery tab (children 3)
 Identifier tab
 Columns definition (children 1)
  ExpressionList (children 1)
   ColumnDeclaration x (children 1)
    DataType Nullable (children 1)
     ExpressionList (children 1)
      DataType UInt8
 Storage definition (children 3)
  Function MergeTree
  Identifier x
  Set