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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 validate_subnet(s):
 """Validate a dotted-quad ip address including a netmask. The string is considered a valid dotted-quad address with netmask if it consists of one to four octets (0-255) seperated by periods (.) followed by a forward slash (/) and a subnet bitmask which is expressed in dotted-quad format. True True True False False False Traceback (most recent call last):
 TypeError: expected string or unicode :param s: String to validate as a dotted-quad ip address with netmask. :type s: str :returns: ``True`` if a valid dotted-quad ip address with netmask, ``False`` otherwise. :raises: TypeError """

    if isinstance(s, basestring):
        if '/' in s:
            start, mask = s.split('/', 2)
            return validate_ip(start) and validate_netmask(mask)
        else:
            return False
    raise TypeError("expected string or unicode")