An introduction to the system containing this package may be found at here (PDF format). These are the slides presented at the WZ group meetings on august 2, 16 and 30. You may also try to grab the slides from here (PDF format this second location might be updated more frequently). These slides may be out of date by the time you look at the code of the analysis_example, but they should nevertheless be useful to new users of the D0 analysis software.