## 5.2.1 Normal Usage

In normal use, end each module `M` with:

      def _test():
          import doctest, M           # replace M with your module's name
          return doctest.testmod(M)   # ditto

      if __name__ == "__main__":
          _test()

Then running the module as a script causes the examples in the docstrings to get executed and verified:

      python M.py

This won't display anything unless an example fails, in which case the failing example(s) and the cause(s) of the failure(s) are printed to stdout, and the final line of output is `'Test failed.'`.

Run it with the -v switch instead:

      python M.py -v

and a detailed report of all examples tried is printed to `stdout`, along with assorted summaries at the end.

You can force verbose mode by passing `verbose=1` to testmod, or prohibit it by passing `verbose=0`. In either of those cases, `sys.argv` is not examined by testmod.

In any case, testmod returns a 2-tuple of ints `(f, t)`, where f is the number of docstring examples that failed and t is the total number of docstring examples attempted.