Explain EXPLAIN SYNTAX (children 1)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 2)
    ExpressionList (children 1)
     Literal UInt64_1
    Function in (children 1)
     ExpressionList (children 2)
      Literal UInt64_1
      Literal Tuple_(UInt64_0, UInt64_1, UInt64_2)