Question about querying a single resource with flask sqlalchemy example.

I have followed the example at http://docs.graphene-python.org/projects/sqlalchemy/en/latest/tutorial/#testing-our-graphql-schema and have a question.

I can issue the following query to list all employees and their departments.

```
{
allEmployees {
edges {
node {
name
department {
name
}
}
}
}
}
```

I would like to be able to query a single employee name and their department name by employee id. I can query using the Node interface, but that doesn't allow me to access Employee name field. Am I supposed to "cast" this to the specific Employee type to do that? What I would like is something like:

```
{
employee(id: "someid") {
name
department {
name
}
}
```

Is this reasonable or am I "doing it wrong"? What is best practice for accessing a single employee using the Relay connections/nodes/edges paradigm?

Many thanks in advance!