Just noticed that to get a dashed line in a line plot:

plt.plot([1, 2, 3, 4], [1, 2, 3, 4], '--')

is completely different from how to specify a line style elsewhere, such as bar():

plt.bar([1, 2, 3, 4], [1, 2, 3, 4], ls='dashed')

It would make sense to me to normalize these two specifications together so that either "accent" of linestyle specifications would work anywhere a "linestyle" argument is accepted.