code: public Parameters pick(String... paths) {
  		Parameters result = new Parameters();
  		for (String path : paths) {
  			if (containsKey(path))
  				result.put(path, get(path));
  		}
  		return result;
  	}
docs: Picks select parameters from this Parameters and returns them as a new
  Parameters object.
  
  @param paths keys to be picked and copied over to new Parameters.
  @return a new Parameters object.