def hamming(a: str, b: str) -> int:
    """Compute the Hamming distance between two strings."""
    ...


def levenshtein(a: str, b: str) -> int:
    """Compute the Levenshtein distance between two strings."""
    ...


def needleman_wunsch(a: str, b: str) -> int:
    """Compute the Needleman-Wunsch distance between two strings."""
    ...
