title: Can I use opam to make a package out of a local file and install it?
body: <p>I'm new to opam and trying to figure out how to use it properly.  For a class, I want to set up students with an environment that has some custom packages installed.  (The package will consist of some raw .ml files that I got from a colleague at another school; the files are on their github but there's no .opam file that I can see, and as far as I know they're not in any official package release.)</p>
  
  <p>Can I somehow call these local .ml files a package and ask opam to install it?  Do the files have to be on github first, and if so can I use my colleague's existing repository as the source?  I don't want to make any of this public, since it is not my own work; I just want to configure my local environment so that the code in the files can be included easily as a package.  Basically I don't know the best way to proceed so I'm happy for any advice.</p>