In Chapter 12, you created a fictional Island::Plotting::Maps module, and built the right support for Exporter so that you could include use Island::Plotting::Maps in a program.
While the resulting .pm file is useful, it's not very practical. There's a lot more to building a real module than just creating the .pm file. You'll also need to consider and implement the following questions:
How and where is the .pm file installed so a program can find the module in its @INC path?
Where is the documentation for the module? How is the documentation installed so the user can read it?
If there are any accompanying files, where are they? How can the end user know if any missing files are missing?
What test harnesses can the developer run to verify correct operation, including testing against older known bugs? Can these same tests be run by the installer to ensure proper operation in the target environment?
If the module contains C or C++ code (not covered here), how can the developer describe how to compile and link the code in the developer's environment, or the end user environment?
As Roy Scheider uttered in the movie Jaws: "You're gonna need a bigger boat." That "bigger boat" is the difference between a module and a distribution.