How to disable introspection on graphene-python?

Question

The docs give this explanation:

validation_errors = validate(
    schema=schema.graphql_schema,
    document_ast=parse('THE QUERY'),
    rules=(
        DisableIntrospection,
    )

... but leave a "THE QUERY" placeholder for the document_ast parameter.

What should be used so that introspection is disabled for all queries?