def __init__(self, value, char,
            desc = None,
            default = False,
            ):
        self.value = value
        if not isinstance(char, str):
            raise ValueError('char must be a string')
        if not (char == '' or len(char) == 1):
            raise ValueError('char must be a single character')
        self.char = char
        self.desc = desc
        self.default = default
Check that L{ProxyClientFactory.clientConnectionFailed} produces
dataset/ETHPy150Open NVIDIA/DIGITS/digits/config/prompt.py/Suggestion.__init__--crossover with--dataset/ETHPy150Open twisted/twisted/twisted/web/test/test_proxy.py/ProxyClientFactoryTests.test_connectionFailed