Live pipeline visualization

[CJ-Wright]

It would be great to visualize data's progress through the pipeline.

This could be accomplished by:

1. Building a live updating graph plot
2. Monkey patching the update methods on all the nodes with a function decorator. This decorator would turn the node yellow when data goes into the update and green when data came out. It may be possible to have it turn red if the data causes an exception.

def visualization_decorator(func):
    def inner(self, data):
        self.v.turn_yellow()
        try:
            func(data)
        except Exception as e:
            self.v.turn_red()
            raise e
        else:
            self.v.turn_green()

[CJ-Wright]

Maybe use grave? https://github.com/networkx/grave