code: public static Deferred<Annotation> getAnnotation(final TSDB tsdb, 
        final String tsuid, final long start_time) {
      if (tsuid != null && !tsuid.isEmpty()) {
        return getAnnotation(tsdb, UniqueId.stringToUid(tsuid), start_time);
      }
      return getAnnotation(tsdb, (byte[])null, start_time);
    }
docs: Attempts to fetch a global or local annotation from storage
  @param tsdb The TSDB to use for storage access
  @param tsuid The TSUID as a string. May be empty if retrieving a global
  annotation
  @param start_time The start time as a Unix epoch timestamp
  @return A valid annotation object if found, null if not