CreateQuery mt (children 3)
 Identifier mt
 Columns definition (children 1)
  ExpressionList (children 2)
   ColumnDeclaration a (children 1)
    DataType UInt64
   ColumnDeclaration b (children 1)
    DataType UInt64
 Storage definition (children 3)
  Function MergeTree
  Identifier a
  Set
