I find the usage of linestyle very _unconvenient_, since there are these two options - linestyle='--' and linestyle='dashed' - which are not exchangable.
I had some code where I initially used the Line2D class, so I had to use linestyle='--'. Now I changed my code to use a LineCollection. LineCollection doesn't work with linestyle='--', but requires linestyle='dashed' - and contrawise Line2D doesn't accept linestyle='dashed', but requires linestyle='--'.
Isn't it possible - and desirable - to unify the usage of linestyle ?