Level 1Exercise #5

Unique letter inventory

Return distinct lowercase alphabetic characters; ignore spaces, digits, and punctuation.

Sample Test Cases

Example #1

Input:unique_letters("OA prep: Day 1!")

Output:{'a','d','e','o','p','r','y'}

Reveal Reference Solution

def unique_letters(text: str) -> set[str]:
    return {ch.lower() for ch in text if ch.isalpha()}

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