class Ping:


    def __init__(self):
        self.__lista_IP = ['host1','host2','host3']
        self.__Find_active_IP(self.__lista_IP)


    def __Find_active_IP(self, lista_IP):

        try:
            logging.debug('def __Trova_nodi')

            for IP in lista_IP:
                try:
                    retcode = subprocess.call("ping " + IP, shell = True)
                    if retcode != 0:
                        lista_IP.remove(IP)
                        print IP + ' FAIL: it doesn't reply'
                    else:
                        print IP + ' OK: it is active'

                except OSError as e:
                    print str(e)

            print self.__lista_IP

        except Exception as e:
            print str(e)



if __name__=='__main__':
    run = Ping()

127.0.0.1 host1
127.0.0.1 host2
127.0.0.1 host3

ping: unknown host host1
host1 FAIL: it doesn't reply
ping: unknown host host3
host3 FAIL: it doesn't reply
['host2']