'Set channel prefetch_count setting.'

def set(self, pcount):

    if (pcount != self.prev):
        new_value = pcount
        if (pcount > PREFETCH_COUNT_MAX):
            logger.warn(u'QoS:    Disabled:    prefetch_count    exceeds    %r', PREFETCH_COUNT_MAX)
            new_value = 0
        logger.debug(u'basic.qos:    prefetch_count->%s', new_value)
        self.callback(prefetch_count=new_value)
        self.prev = pcount
    return pcount
