from typing import List


def chunk(s: str, n: int = 80) -> List[str]:
    """Chunk string into segments of specified length.

    >>> chunk(('wordsX' * 5), 11)
    ['wordsXwords', 'XwordsXword', 'sXwordsX']
    >>> chunk('x', 80)
    ['x']
    """
    return [s[i:i + n] for i in range(0, len(s), n)]