Error: Error handler;
</li><li> IO r: Action that defines the worker's lifetime.
</li></ul></div></div><h1 id="g:7">More about Registries
</h1><div class="doc"><p>Until now, we have only looked at how to connect to a registry,
     not at how to use it and what a registry actually is in terms of
     data types.
     Well, answering the second question is simple:
     a registry, from the perspective of the user application,
     is an opaque data type with a set of functions:
</p></div><div class="top"><p 