Explain EXPLAIN SYNTAX (children 1)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 2)
    ExpressionList (children 1)
     Literal Array_[UInt64_3, UInt64_4, UInt64_5] (alias x)
    ExpressionList (children 1)
     Function CAST (children 1)
      ExpressionList (children 2)
       Function arrayElement (children 1)
        ExpressionList (children 2)
         Identifier x
         Literal UInt64_1
       Literal \'Int32\'
