python example "Example program: Plotter" - is broken

[123mitnik]

running the python Example program: Plotter (example-plot.md) on OSX with

(base) ➜  ~ python --version
Python 3.7.6

RuntimeWarning: coroutine 'TectonicDB.cmd' was never awaited
    self.db.cmd("USE {}".format(market).encode())[1]
RuntimeWarning: Enable tracemalloc to get the object allocation traceback
Traceback (most recent call last):
    self.db.cmd("USE {}".format(market).encode())[1]
TypeError: 'coroutine' object is not subscriptable

rustc 1.49.0 (e1884a8e3 2020-12-29)