code: func IsDateFormat(format string) bool {
  	format = strings.TrimSpace(format)
  	seps := ParseDateFormat(format)
  	length := len(format)
  	switch len(seps) {
  	case 1:
  		if (length == 8) || (length == 6) {
  			return true
  		}
  	case 3:
  		return true
  	}
  	return false
  }
docs: // IsDateFormat returns true when the specified time format could contain only date.