from typing import List
from typing import Tuple


def find_next_docstring(contents: List[str], index: int) -> Tuple[int, int]:
    """
    Finds next docstring in contents starting from index. Returns (-1, -1) if no docstring found.

    :param contents: list of lines in file
    :param index: index to start looking for docstring
    :return: start and end position of docstring
    """
    possible_docstring_start = ['"""', "'''", 'r"""', "r'''"]
    corresponding_docstring_end = {
        '"""': '"""',
        "'''": "'''",
        'r"""': '"""',
        "r'''": "'''",
    }

    for i in range(index, len(contents)):
        line = contents[i].strip()
        if line in possible_docstring_start:
            for j in range(i + 1, len(contents)):
                next_line = contents[j].strip()
                if next_line == corresponding_docstring_end[line]:
                    return i, j

    return -1, -1