A single doctest example, consisting of source code and expected output. `Example` defines the following attributes:

• source: A single Python statement, always ending with a newline. The constructor adds a newline if needed.

• want: The expected output from running the source code (either from stdout, or a traceback in case of exception). `want` ends with a newline unless it's empty, in which case it's an empty string. The constructor adds a newline if needed.

• exc_msg: The exception message generated by the example, if the example is expected to generate an exception; or `None` if it is not expected to generate an exception. This exception message is compared against the return value of `traceback.format_exception_only()`. `exc_msg` ends with a newline unless it's `None`. The constructor adds a newline if needed.

• lineno: The line number within the DocTest string containing this Example where the Example begins. This line number is zero-based, with respect to the beginning of the DocTest.

• indent: The example's indentation in the DocTest string. I.e., the number of space characters that preceed the example's first prompt.

• options: A dictionary mapping from option flags to True or False, which is used to override default options for this example. Any option flags not contained in this dictionary are left at their default value (as specified by the DocTestRunner's optionflags). By default, no options are set.

__init__ (
        self,
        source,
        want,
        exc_msg=None,
        lineno=0,
        indent=0,
        options=None,
        )