nfc raspberrypi return true? tag?

true

import nfc
import time

def connected (tag):
    print('connected!!')
    time.sleep(1)
    return 1

clf = nfc.ContactlessFrontend('usb')

while True:
    print('waiting...')
    result = clf.connect(rdwr={'on-connect':connected})
    print(result)
    print('scaned')

とやると, なぜか

waiting...
connected!!
True
scaned
waiting...
connected!!
True
scaned
waiting...

のようにtrueがでる.

tag

一方, returnに何も入れずに

import nfc
import time

def connected (tag):
    print('connected!!')
    time.sleep(1)
    return

clf = nfc.ContactlessFrontend('usb')

while True:
    print('waiting...')
    result = clf.connect(rdwr={'on-connect':connected})
    print(result)
    print('scaned')

とすると,

waiting...
connected!!
Type3Tag ID=01010501b00ac30b PMM=03014b024f4993ff SYS=1234
scaned
waiting...
connected!!
Type3Tag ID=01010501b00ac30b PMM=03014b024f4993ff SYS=1234
scaned
waiting...

のようにtagがreturnされる.
まぁこれは理解できる…か.
でもreturn 1 でtrueになるのはやっぱ謎.