SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 1)
    Function toDecimal64 (alias x) (children 1)
     ExpressionList (children 2)
      Literal Float64_2.1
      Literal UInt64_4
   ExpressionList (children 1)
    Identifier x