code: func (s *StaticSource) NextLogEntry() (le *logpb.LogEntry, err error) {
  	// Pop the next entry, mutating s.
  	if len(*s) > 0 {
  		le, *s = (*s)[0], (*s)[1:]
  	}
  	if len(*s) == 0 {
  		err = io.EOF
  	}
  	return
  }
docs: // NextLogEntry implements Source.