As seen in TeamService2.ts, the Contextual type will add Context as the
last argument to any method of the interface, as long as the method has
0-4 arguments.
Interfaces with more than 4 arguments cannot use this type, but they
could be converted to interfaces which use 1 argument
(object/dictionary) only.
Some long-term thinking: Maybe only methods with a single argument
should be supported, similar to the way gRPC does it.
