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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(self, ticket, client_ip=None, now=None, encoding='utf-8'):
 """Validates the passed ticket, , raises a TicketError on failure Args: ticket: String value (possibly generated by new function) client_ip: Optional IPAddress of client, should be passed if the ip address was passed on ticket creation. now: Optional (defaults to time.time()) time to use when validating ticket date Returns: Ticket a TicketInfo tuple containing the users authentication details on success Raises: TicketParseError: Invalid ticket format TicketDigestError: Digest is incorrect (ticket data was modified) TicketExpired: Ticket has passed expiration date """

        parts = self.parse(ticket)

        # Check if our ticket matches
        new_ticket = self.new(*(parts[1:]), client_ip=client_ip, encoding=encoding)

        if new_ticket[:self._hash.digest_size * 2] != parts.digest:
            raise TicketDigestError(ticket)

        if now is None:
            now = time.time()

        if parts.valid_until <= now:
            raise TicketExpired(ticket)

        return parts