def on_print(self, node):    # ('dest', 'values', 'nl')
        dest = self.run(node.dest) or self.writer
        end = ''
        if node.nl:
            end = '\n'
        out = [self.run(tnode) for tnode in node.values]
        if out and len(self.error)==0:
            print(*out, file=dest, end=end)
Registers a new watch under [key] (which can be used with `unwatch()`
dataset/ETHPy150Open xraypy/xraylarch/lib/interpreter.py/Interpreter.on_print--crossover with--dataset/ETHPy150Open cemerick/nrepl-python-client/nrepl/__init__.py/WatchableConnection.watch