Explain EXPLAIN SYNTAX (children 1)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 2)
    ExpressionList (children 1)
     Function if (children 1)
      ExpressionList (children 3)
       Function equals (children 1)
        ExpressionList (children 2)
         Identifier number
         Literal UInt64_1
       Literal \'hello\'
       Function if (children 1)
        ExpressionList (children 3)
         Function equals (children 1)
          ExpressionList (children 2)
           Identifier number
           Literal UInt64_2
         Literal \'world\'
         Literal \'xyz\'
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       Function numbers (children 1)
        ExpressionList (children 1)
         Literal UInt64_10