code: func (j *JSONSource) Record() (interface{}, error) {
  	rec, ok := <-j.records
  	if !ok {
  		return nil, io.EOF
  	}
  	return rec.data, rec.err
  }
docs: // Record returns an unmarshaled json document as a map[string]interface. That
  // is, the resulting interface{} can be cast to a map[string]interface{}.