code: function processFile(file, cb) {
          var data = dataSource(file);
          return pickTemplate(
              forcedTemplateName
                  || getTemplateName(data)
                  || defaultTemplateName)
              .then(function(template) {
                  file.path = replaceExt(file.path, '.html');
  
                  data._file= file;
                  data._target = {
                      path: file.path,
                      relative: replaceExt(file.relative, '.html'),
                  };
  
                  // data = dataParser(data);
  
                  var result = template.render(data);
  
                  file.contents = new Buffer(result, 'utf-8');
                  return file;
              });
      }
docs: Process one input file, may return a promise or throw an exception