code: public synchronized PID generatePID(String namespace) throws IOException {
          int i = getHighestID(namespace);
          i++;
  
          try {
              m_lastPID = new PID(namespace + ":" + i);
          } catch (MalformedPIDException e) {
              throw new IOException(e.getMessage());
          }
  
          setHighestID(namespace, i);
  
          return m_lastPID;
      }
docs: Generate a new pid that is guaranteed to be unique, within the given
  namespace.