Some docstrings.

def signal(e):
    """
    Some docstrings.
    """
    callback = find_handler(e)
    if callback is None:
        if _activate_debugger:
            print 'Handler for error {0} not found'.format(type(e))
            traceback.print_stack()
            set_trace()
        raise e
    else:
        return callback(e)