When plotting multiple different versions together, it is useful if they can be visually told apart by using a different linestyle. Since the only input data is the file path and the shotgun JSON itself, provide the user with an option to change the linestyle based on the file name, which is also used as the chart label.
A choice to use regular expression was made to keep maximum flexibility for future use. The supported linestyles are limited to four predefined named choices which matplotlib supports [1]. A short consideration to support parametrized linestyles was made, but for simplicity's sake, it was decided that four linestyles are sufficient for everybody ;)
[1] - https://matplotlib.org/stable/gallery/lines_bars_and_markers/linestyles.html