A single interactive example, consisting of a Python statement and
its expected output. The constructor arguments are used to
initialize the member variables of the same names.
New in version 2.4.
Example defines the following member variables. They are
initialized by the constructor, and should not be modified directly.
source
A string containing the example's source code. This source code
consists of a single Python statement, and always ends with a
newline; the constructor adds a newline when necessary.
want
The expected output from running the example's source code (either
from stdout, or a traceback in case of exception). want
ends with a newline unless no output is expected, in which case
it's an empty string. The constructor adds a newline when
necessary.
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 string containing this example where
the example begins. This line number is zero-based with respect
to the beginning of the containing string.
indent
The example's indentation in the containing string, i.e., the
number of space characters that precede 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.
