A Contribution instance represents an invidividual heatmap node, with
a heat level corresponding to the data-level attribute set on the scraped
SVG Rect element.
A ContributionWeek instance represents an entire week of contributions
in a Github contribution heatmap. Typically visible as a column of heatmap
nodes on a Github profile page.
Attempts to parse a Github profile slug, based on a regular expression
typically used while restricting profile names. Assures that only
valid profile slugs are being provided as an argument to Clap.
Attempts to parse a provided Year argument, based on simple regular
expression. Assures that only valid calendar years are being provided
as an argument to clap.