format files to black style

4 jobs for add_back_hook in 2 minutes and 54 seconds (queued for 1 second)
Status Job ID Name Coverage
  Style
passed #135504
check_style

00:00:18

 
  Test Library
passed #135505
test:python3.5-stretch-pyqt5

00:01:15

passed #135506
test:python3.7_stretch_pyqt5

00:01:11

 
  Test Notbooks
passed #135507
test:test-tomoscan-tutorials

00:01:20