def METHOD_NAME(app):
    app.add_node(SmithyTraitIndexNode)
    app.add_directive("smithy-trait", SmithyTraitDirective)
    app.add_directive("smithy-trait-index", SmithyTraitIndexDirective)
    app.connect("doctree-resolved", process_smithy_nodes)
    app.connect("env-purge-doc", purge_smithy_traits)
    app.connect("env-merge-info", merge_smithy_traits)