code: func NotBlank(fl validator.FieldLevel) bool {
  	field := fl.Field()
  
  	switch field.Kind() {
  	case reflect.String:
  		return len(strings.TrimSpace(field.String())) > 0
  	case reflect.Chan, reflect.Map, reflect.Slice, reflect.Array:
  		return field.Len() > 0
  	case reflect.Ptr, reflect.Interface, reflect.Func:
  		return !field.IsNil()
  	default:
  		return field.IsValid() && field.Interface() != reflect.Zero(field.Type()).Interface()
  	}
  }
docs: // NotBlank is the validation function for validating if the current field
  // has a value or length greater than zero, or is not a space only string.