anchor.diff:  }
   
   Future<SqlResultSet> queryTable(SqlTransaction transaction, String tableName) {
  -  final completer = new Completer<SqlResultSet>();
  +  final completer = new Completer<SqlResultSet>.sync();
   
     final sql = 'SELECT * FROM $tableName';
     transaction.executeSql(sql, [],
  
positive.code: 
  Future<SqlResultSet> dropTable(SqlTransaction transaction, String tableName,
      [bool ignoreFailure = false]) {
    final completer = new Completer<SqlResultSet>();
  
    final sql = 'DROP TABLE $tableName';
    transaction.executeSql(sql, [],
  
negative.code: 
  Future<SqlResultSet> createTable(SqlTransaction transaction, String tableName,
      String columnName) {
    final completer = new Completer<SqlResultSet>.sync();
  
    final sql = 'CREATE TABLE $tableName ($columnName)';
    transaction.executeSql(sql, [],
  