---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-69-0aeb77ed27a7> in <module>
     16
     17 # задаем масштаб осей
---> 18 plt.axis(["2019-08-01", '2019-08-31'])

/opt/conda/lib/python3.7/site-packages/matplotlib/pyplot.py in axis(*args, **kwargs)
   2410 @docstring.copy(Axes.axis)
   2411 def axis(*args, **kwargs):
-> 2412     return gca().axis(*args, **kwargs)
   2413
   2414

/opt/conda/lib/python3.7/site-packages/matplotlib/axes/_base.py in axis(self, *args, **kwargs)
   1730
   1731         if len(v) != 4:
-> 1732             raise ValueError('args must contain [xmin xmax ymin ymax]')
   1733
   1734         self.set_xlim([v[0], v[1]], emit=emit, auto=False)

ValueError: args must contain [xmin xmax ymin ymax]