lanation of the error.

        By default, this will use the current C{exception}
        (L{sys.exc_info}()).  However, if you want to specify a
        particular kind of failure, you can pass an exception as an
        argument.

        If no C{exc_value} is passed, then an "original" C{Failure} will
        be searched for. If the current exception handler that this
        C{Failure} is being constructed in is handling an exception
        raised by L{raiseException}, then this C{Failure} will act like
        the original C{Failure}.

        For C{exc_tb} only L{traceback} instances or L{None} are allowed.
        If L{None} is supplied for C{exc_value}, the value of C{exc_tb} is
        ignored, otherwise if C{exc_tb} is L{None}, it will be found from
        execution context (ie, L{sys.exc_info}).

        @param captureVars: if set, capture locals and globals of stack
            frames.  This is pretty slow, and makes no difference unless you
            are going to use L{printDetailedTraceback}.
        é