Explain EXPLAIN SYNTAX (children 1)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 3)
    ExpressionList (children 2)
     Function plus (children 1)
      ExpressionList (children 2)
       Function cityHash64 (children 1)
        ExpressionList (children 1)
         Identifier a
       Literal UInt64_10
     Function plus (children 1)
      ExpressionList (children 2)
       Identifier b
       Literal UInt64_3
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       TableIdentifier column_swap_test_test
    Function equals (children 1)
     ExpressionList (children 2)
      Identifier b
      Literal UInt64_0