1. download the Java class file vec2d.class and test with the documention
2. write any bug you find in a file named bugs.txt and upload to your svn folder
   under lab23mar/ subfolder. Your notes in bugs.txt should be sufficient for yourself to
   quickly reproduce the error cause by the bug you found after long time, let's say a year.
3. this lab does not count for final marks but makes sure you know how to do testing