code: func (d Decoder) UnmarshalToMap(data []byte, f Format) (map[string]interface{}, error) {
  	m := make(map[string]interface{})
  	if data == nil {
  		return m, nil
  	}
  
  	err := d.unmarshal(data, f, &m)
  
  	return m, err
  }
docs: // UnmarshalToMap will unmarshall data in format f into a new map. This is
  // what's needed for Hugo's front matter decoding.