te examples.  By
    default, no extra globals are used.  This is new in 2.4.

    Optional keyword arg "verbose" prints lots of stuff if true, prints
    only failures if false; by default, it's true iff "-v" is in sys.argv.

    Optional keyword arg "report" prints a summary at the end when true,
    else prints nothing at the end.  In verbose mode, the summary is
    detailed, else very brief (in fact, empty if all tests passed).

    Optional keyword arg "optionflags" or's together module constants,
    and defaults to 0.  This is new in 2.3.  Possible values (see the
    docs for details):

        DONT_ACCEPT_TRUE_FOR_1
        DONT_ACCEPT_BLANKLINE
        NORMALIZE_WHITESPACE
        ELLIPSIS
        SKIP
        IGNORE_EXCEPTION_DETAIL
        REPORT_UDIFF
        REPORT_CDIFF
        REPORT_NDIFF
        REPORT_ONLY_FIRST_FAILURE

    Optional keyword arg "raise_on_error" raises an exception on the
    first unexpected exception or failure. This allows failures to be
    post-mortem debugged.

    Advanced tomfoolery:  testmod runs methods of a local instance of
    class doctest.Tester, then merges the results into (or creates)
    global Tester instance doctest.master.  Methods of doctest.master
    can be called directly too, if you want to do something unusual.
    Passing report=0 to testmod is especially useful then, to delay
    displaying a summary.  Invoke doctest.master.summarize(verbose)
    when you're done fiddling.
    Nr£