code: func (w *FreqProxTermsWriterPerField) start(f IndexableField, first bool) bool {
  	w.TermsHashPerFieldImpl.start(f, first)
  	w.payloadAttribute = w.fieldState.payloadAttribute
  	w.offsetAttribute = w.fieldState.offsetAttribute
  	return true
  }
docs: /* Called after flush */
  // func (w *FreqProxTermsWriterPerField) reset() {
  // 	// record, up front, whether our in-RAM format will be
  // 	// with or without term freqs:
  // 	w.setIndexOptions(w.fieldInfo.IndexOptions())
  // 	w.payloadAttribute = nil
  // }
  // func (w *FreqProxTermsWriterPerField) setIndexOptions(indexOptions IndexOptions) {
  // 	if n := int(indexOptions); n > 0 {
  // 		w.hasFreq = n >= int(INDEX_OPT_DOCS_AND_FREQS)
  // 		w.hasProx = n >= int(INDEX_OPT_DOCS_AND_FREQS_AND_POSITIONS)
  // 		w.hasOffsets = n >= int(INDEX_OPT_DOCS_AND_FREQS_AND_POSITIONS_AND_OFFSETS)
  // 	} else {
  // 		// field could later be updated with indexed=true, so set everything on
  // 		w.hasFreq = true
  // 		w.hasProx = true
  // 		w.hasOffsets = true
  // 	}
  // }
  // func (w *FreqProxTermsWriterPerField) start(fields []IndexableField, count int) (bool, error) {
  // 	for _, field := range fields[:count] {
  // 		if field.FieldType().Indexed() {
  // 			return true, nil
  // 		}
  // 	}
  // 	return false, nil
  // }