SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 1)
    Function mapAdd (children 1)
     ExpressionList (children 2)
      Function map (children 1)
       ExpressionList (children 4)
        Literal \'a\'
        Literal UInt64_1
        Literal \'b\'
        Literal UInt64_1
      Function map (children 1)
       ExpressionList (children 2)
        Identifier key
        Literal UInt64_1
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      Function values (children 1)
       ExpressionList (children 4)
        Literal \'key String\'
        Literal \'b\'
        Literal \'c\'
        Literal \'d\'
