code: public void write(File file) throws Exception {
          try {
              FileOutputStream fos = new FileOutputStream(file);
              write(fos);
          } catch (Exception e) {
              e.printStackTrace();
              throw e;
          }
      }
docs: the method to write the R2RML mappings
  from an rdf Model to a file
  
  @param file the ttl file to write to