APEX

Hi experts,

I'm using APEX 5.0 and would like to generate a JSON Payload like this:

 {"assigned_id": ""}

But don't know how to make it with apex_json.write. Whole sample would be:

BEGIN
  apex_json.initialize_clob_output;
  apex_json.open_object;
  apex_json.write('assigned_id', '');
  apex_json.close_object;
  dbms_output.put_line(apex_json.get_clob_output);
  apex_json.free_output;
END;

Thanks in advance,
Jose.