code: function outputPath(options, source) {
      var DEBUG = false;
      if (DEBUG)
          console.log('sourceFolder: ' + options.sourceFolder);
      var globBase = options.sourceFolder.replace(/\*.*/, '');
      if (globBase.endsWith('.sol')) // single file
          globBase = path.join(globBase, '../');
      if (DEBUG)
          console.log('globBase: ' + globBase);
      var optDestination = options.destinationFolder ? options.destinationFolder : globBase;
      if (DEBUG)
          console.log('optDestination: ' + optDestination);
      var destinationFolder = path.join(globBase, optDestination);
      if (optDestination === globBase)
          destinationFolder = globBase;
      if (DEBUG)
          console.log('destinationFolder: ' + destinationFolder);
      // destination-folder is absolut
      if (options.destinationFolder && options.destinationFolder.startsWith('/'))
          destinationFolder = path.join(options.destinationFolder, './');
      var fileNameRelative = source.filename.replace(globBase, '');
      if (DEBUG)
          console.log('fileNameRelative: ' + fileNameRelative);
      var goalPath = path.join(destinationFolder, fileNameRelative);
      return goalPath;
  }
docs: determines where the output should be written