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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 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)