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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _unquote_cookie(s: str) -> str: """Handle double quotes and escaping in cookie values. This method is copied verbatim from the Python 3.5 standard library (http.cookies._unquote) so we don't have to depend on non-public interfaces. """

    # If there aren't any doublequotes,
    # then there can't be any special characters.  See RFC 2109.
    if s is None or len(s) < 2:
        return s
    if s[0] != '"' or s[-1] != '"':
        return s

    # We have to assume that we must decode this string.
    # Down to work.

    # Remove the "s
    s = s[1:-1]

    # Check for special sequences.  Examples:
    #    \012 --> \n
    #    \"   --> "
    #
    i = 0
    n = len(s)
    res = []
    while 0 <= i < n:
        o_match = _OctalPatt.search(s, i)
        q_match = _QuotePatt.search(s, i)
        if not o_match and not q_match:  # Neither matched
            res.append(s[i:])
            break
        # else:
        j = k = -1
        if o_match:
            j = o_match.start(0)
        if q_match:
            k = q_match.start(0)
        if q_match and (not o_match or k < j):  # QuotePatt matched
            res.append(s[i:k])
            res.append(s[k + 1])
            i = k + 2
        else:  # OctalPatt matched
            res.append(s[i:j])
            res.append(chr(int(s[j + 1 : j + 4], 8)))
            i = j + 4
    return _nulljoin(res)