E901,E999,F821,F822,F823 are the "showstopper" flake8 issues that can halt the runtime with a SyntaxError, NameError, etc. These 5 are different from most other flake8 issues which are merely "style violations" -- useful for readability but they do not effect runtime safety.
F821: undefined name name
F822: undefined name name in __all__
F823: local variable name referenced before assignment
E901: SyntaxError or IndentationError
E999: SyntaxError -- failed to compile a file into an Abstract Syntax Tree
flake8 testing of https://github.com/Pylons/pyramid_cookbook on Python 3.7.1
$ flake8 . --count --select=E901,E999,F821,F822,F823 --show-source --statistics
E901,E999,F821,F822,F823 are the "showstopper" flake8 issues that can halt the runtime with a SyntaxError, NameError, etc. These 5 are different from most other flake8 issues which are merely "style violations" -- useful for readability but they do not effect runtime safety.
name
name
in__all__