code: func (f *FieldHeaderNames) Set(value string) error {
  	// When arguments are passed through YAML, escaped double quotes
  	// might be added to this string, and they would break the last
  	// key/value pair. This ensures the string is clean.
  	value = strings.Trim(value, "\"")
  
  	fields := strings.Fields(value)
  
  	for _, field := range fields {
  		n := strings.SplitN(field, "=", 2)
  		(*f)[n[0]] = n[1]
  	}
  
  	return nil
  }
docs: // Set is the method to set the flag value, part of the flag.Value interface.
  // Set's argument is a string to be parsed to set the flag.
  // It's a space-separated list, so we split it.