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undefined-name (F821)#

Derived from the Pyflakes linter.

What it does#

Checks for uses of undefined names.

Why is this bad?#

An undefined name is likely to raise NameError at runtime.

Example#

def double():
    return n * 2  # raises `NameError` if `n` is undefined when `double` is called

Use instead:

def double(n):
    return n * 2

Options#

  • target-version: Can be used to configure which symbols Ruff will understand as being available in the builtins namespace.

References#