Rename function.

Rename the internal_get_stream function to be a different arty of the
get_stream call.
Remove useless comment.

Remove a comment which is no longer needed.
Add program registration.

Add a prototype implementation of allowing an entire derflow program to
be run at a given virtual node.

Program registration assumes the file is located and available at each
node.
Return result.

When executing a remote program, return the result of the program to
the caller.
Add parse transformation.

Add a parse transformation for identifying calls to derflow, which is
used when remotely registering programs.