As usual, create two directories for today's class.  Create a
directory called lecture25 under activities, and
a directory called lab25 under labs.
  For the following function header, write some tests cases that you
  could execute on that code.  Write these test cases in a file
  called base_test_cases.py in your lecture25
  directory.
#Pre: to_convert is an integer >= 0, the number to have its base # converted. # base is an integer in the range [1,36], the base to convert # to_convert to. #Post: Returns a string, the base 'base' encoding of the to_convert # integer. def convert_base(to_convert, base)