Question: How can we obtain the absolute path to a file whose path relative to the current .mpl file we know?

Let's say I have a file test.mpl file in the path ~/maple/Packages/MyPackage/test.mpl.

From the code in this file, I wish to save something to a file in the directory at the relative path ./Animations, which has absolute path ~/maple/Packages/MyPackage/Animations.

Now, on my machine, because I know the path to this directory I can easily save using the absolute path. 

What if I send this directory MyPackage (which is essentially a package) to someone else. Maybe they keep it in a different location such as ~/projects/maple-projects/MyPackage.

I would like that this person be able to run test.mpl and it will save the aforementioned something to a file in the relative location ./Animations, which on their machine is the absolute path ~/projects/maple-projects/MyPackage/Animations.

I am stuck on how to accomplish this.

I found out that if I am in a worksheet that is in the directory MyPackage then I can use interface(worksheetdir) to find out the path to the worksheet, so if everything were run from a worksheet contained in the MyPackages directory then I could use a relative path to the Animations directory. 

Problem is, the normal usage of test.mpl is to just create some new worksheet and read the file and use it. But a new worksheet like this is located in the home directory by default.