Code from Practical Python.

The "porty" directory is a Python package of code that's loaded via 
import.  The "print-report.py" program is a top-level script that
produces a report.  Try it:

shell % python3 print-report.py portfolio.csv prices.csv txt
      Name     Shares      Price     Change 
---------- ---------- ---------- ---------- 
        AA        100       9.22     -22.98 
       IBM         50     106.28      15.18 
       CAT        150      35.46     -47.98 
      MSFT        200      20.89     -30.34 
        GE         95      13.48     -26.89 
      MSFT         50      20.89     -44.21 
       IBM        100     106.28      35.84 
shell %