docs: public <T> File writeLines(Collection<T> list, LineSeparator lineSeparator, boolean isAppend) throws IORuntimeException {
  		try (PrintWriter writer = getPrintWriter(isAppend)){
  			for (T t : list) {
  				if (null != t) {
  					writer.print(t.toString());
  					printNewLine(writer, lineSeparator);
  					writer.flush();
  				}
  			}
  		}
  		return this.file;
  	}