problem in using pyqrcode module to create QRcode

[snippsat]

# Make environment
C:\code
λ python -m venv qr_env

C:\code
λ cd qr_env\

C:\code\qr_env
λ C:\code\qr_env\Scripts\activate

# Install
(qr_env) C:\code\qr_env
λ pip install PyQRCode pypng
Collecting PyQRCode
  Using cached PyQRCode-1.2.1-py3-none-any.whl
Collecting pypng
  Using cached pypng-0.20220715.0-py3-none-any.whl (58 kB)
Installing collected packages: PyQRCode, pypng
Successfully installed PyQRCode-1.2.1 pypng-0.20220715.0

(qr_env) C:\code\qr_env
λ ls
Include/  Lib/  Scripts/  pyvenv.cfg  qr_code.py

(qr_env) C:\code\qr_env
λ cat qr_code.py
import pyqrcode

qr=pyqrcode.create('hello')
qr.png('hello.png',scale=7)
(qr_env) C:\code\qr_env

# Run code
λ python qr_code.py
.... No errors

(qr_env) C:\code\qr_env
λ ls
Include/  Lib/  Scripts/  hello.png  pyvenv.cfg  qr_code.py