> structure = json.loads(json_string)

Not quite. Let's say your JSON data contains the following attribute:

    "access" : [ "view", "edit", "admin" ],

This field should be represented (in the language) as a set of values from an "access-levels" enumeration.

In C#, you'd have the following boilerplate:

    [DataMember(Name = "access")]
    public HashSet<AccessLevels> Access { get; private set; }

In OCaml, it would be:

    access : Access.Set.t ;

The simple "json.loads" solution would return a list of strings instead. What's the Python code for turning it into a set of enumeration values, and failing if one of the values does not match ?