ambiguous-variable-name (E741)

Derived from the pycodestyle linter.

What it does

Checks for the use of the characters 'l', 'O', or 'I' as variable names.

Why is this bad?

In some fonts, these characters are indistinguishable from the numerals one and zero. When tempted to use 'l', use 'L' instead.

Example

l = 0
O = 123
I = 42

Use instead:

L = 0
o = 123
i = 42

Preview mode behavior for stub files

In [preview] mode, this rule is automatically disabled for all stub files (files with .pyi extensions). The rule has little relevance for authors of stubs: a well-written stub should aim to faithfully represent the interface of the equivalent .py file as it exists at runtime, including any ambiguously named variables in the runtime module.