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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 activate_host(self, host):
        '''
        Flag a host as active.
        '''

        logger.debug('Activating host: {0}'.format(host))

        # Add to *both* activated and active - active will reduce as hosts fail
        # but connected will not, enabling us to track failed %.
        self.activated_hosts.add(host)
        self.active_hosts.add(host)