An example of how to create your own custom node module; as well as how to use it in your own program.
The example module provided is a simple function that reads command line arguments to print filenames in a directory that a particular file name extension.
I.E. 'print all files in directory that match txt extentsion'.
The program requires that the first command line argument be a path to the directory name of interest, and the second command line argument be a filename extension (with the '.', i.e. 'txt').