import re


def search_end_recursively(lines: str, index: int, size: int = 80) -> int:
    """Search for the index of the last continuation line."""
    patt = r"^\s*&.*"
    while True:
        rs = re.search(patt, lines[index:])
        if rs is None:
            break
        else:
            index += rs.end()

    return index