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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 check_key(self, key):
 """ Check that the key length is valid. @param key: a byte string """

        if self.key_size and len(key) not in self.key_size:
            raise TypeError('invalid key size %s, must be one of %s' %
                            (len(key), self.key_size))