Communication between Raspberry Pi and multiple Arduinos via Bluetooth Low Power (BLE)

raspberrypi2_ble.py

from bluepy.btle import Scanner, DefaultDelegate, Peripheral
import threading

class NotificationDelegate(DefaultDelegate):

    def __init__(self, number):
        DefaultDelegate.__init__(self)
        self.number = number

    def handleNotification(self, cHandle, data):
        print 'Notification:\nConnection:'+str(self.number)+'\nHandler:'+str(cHandle)+'\nMsg:'+data

bt_addrs = ['00:15:83:00:45:98', '00:15:83:00:86:72']
connections = []
connection_threads = []
scanner = Scanner(0)

class ConnectionHandlerThread (threading.Thread):
    def __init__(self, connection_index):
        threading.Thread.__init__(self)
        self.connection_index = connection_index

    def run(self):
        connection = connections[self.connection_index]
        connection.setDelegate(NotificationDelegate(self.connection_index))
        while True:
            if connection.waitForNotifications(1):
                connection.writeCharacteristic(37, 'Thank you for the notification!')

while True:
    print'Connected: '+str(len(connection_threads))
    print 'Scanning...'
    devices = scanner.scan(2)
    for d in devices:
        print(d.addr)
        if d.addr in bt_addrs:
            p = Peripheral(d)
            connections.append(p)
            t = ConnectionHandlerThread(len(connections)-1)
            t.start()
            connection_threads.append(t)

Is there a way to send messages to each client via Bluetooth?