mkhozin-osx:small-test-framework mkhozin$ python3 ../submit.py
Traceback (most recent call last):
  File "../submit.py", line 121, in <module>
    push_branches(task_name)
  File "../submit.py", line 82, in push_branches
    git("push", "-f", "student", "submits/" + task_name)
  File "../submit.py", line 17, in git
    subprocess.check_output(["git"] + list(args), cwd=SHADOW_REPO_DIR, stderr=subprocess.PIPE)
  File "/usr/local/Cellar/python/3.7.5/Frameworks/Python.framework/Versions/3.7/lib/python3.7/subprocess.py", line 411, in check_output
    **kwargs).stdout
  File "/usr/local/Cellar/python/3.7.5/Frameworks/Python.framework/Versions/3.7/lib/python3.7/subprocess.py", line 512, in run
    output=stdout, stderr=stderr)
subprocess.CalledProcessError: Command '['git', 'push', '-f', 'student', 'submits/small-test-framework']' returned non-zero exit status 128.