How to use [validators.enum]

The reference page of validators.enum has its arguments, constraints and declaration.

This validator will throw an exception unless the specified string argument is one of the legal values. Usage could be as follows.

validators.enum:x:@.arguments/*/enum_value
   .:val1
   .:val2

If the above [enum_value] is not either val1 or val2 the validator will throw an exception.