An abstract program runtime for ASTs produced by `ablauf.job.ast`.
This exposes two functions for the outside world: `make`
and `restart`

You are expected to create a *program* to be ran with the functions
available in the `ablauf.job.ast` namespace. This program is then
initialized with the rough equivalent of an instruction pointer and
a context.

This namespace makes no guess as to how program instructions are
actually performed, instead, for each position of the program,
it yields the instructions to carry out. There might be more than
one if parallelism is used.

The logical flow is thus:

- call restart on a program with an empty result list
- carry out resulting actions
- call restart on the result of the actions

For an actual full fledged program runner, a runner using
**manifold** as the underlying dispatching engine is provided
in `ablauf.job.manifold`.

Specifies an AST and provides helper functions
to build it

An execution engine for warp jobs on manifold.
To perform parallel actions with manifold.

Execution is represented as a stream on which results
are produced.

The stream is closed when execution is finished.
Each execution step is store with the help of a
`ablauf.job.store/JobStore` implementation that
needs to be supplied.

This namespace makes no assumption on how to actually
perform side-effects, consumers of `runner` need to
extend the `dispatch-action` multimethod to perform those.

Operations on job nodes (statements) outside zippers