Explain EXPLAIN SYNTAX (children 1)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 3)
    ExpressionList (children 2)
     Function substring (children 1)
      ExpressionList (children 3)
       Function reverse (children 1)
        ExpressionList (children 1)
         Identifier b
       Literal UInt64_1
       Literal UInt64_1
     Identifier a
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       TableIdentifier column_swap_test_test
    Function equals (children 1)
     ExpressionList (children 2)
      Function substring (children 1)
       ExpressionList (children 3)
        Function reverse (children 1)
         ExpressionList (children 1)
          Identifier b
        Literal UInt64_1
        Literal UInt64_1
      Literal \'c\'