0 and O, and l and I that look the same in a single font is a crime of modern typography.

Also, I remember 8x16 VGA font that came with KeyRus had some slight differences between Cyrillic and Latin lookalikes, that brought some strange sense of comfort when reading, and especially typing the letter c, because its Cyrillic lookalike is located on the same key.

The font the arduino editor uses renders l and 1 exactly the same. Utter madness in a beginner programming context.