When working on a pre-existing version of a site, you may need to check if a style is already loaded. This, in and of itself, is not that difficult, but if it’s using an older version of a dependency, then it can get a little more complicated.
For example, let’s say that you’re building a plugin for an existing site. The existing site uses something like Font Awesome, but it’s using an older version.
The requirements call for some updated icons that aren’t available in the existing version. Furthermore, the version of Font Awesome maybe be the minified version or not so we need to check for that.