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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 smart_search_asn(self, auth, query_str, search_options=None, extra_query=None):
 """ Perform a smart search operation among AS numbers * `auth` [BaseAuth] AAA options. * `query_str` [string] Search string * `search_options` [options_dict] Search options. See :func:`search_asn`. * `extra_query` [dict_to_sql] Extra search terms, will be AND:ed together with what is extracted from the query string. Return a dict with three elements: * :attr:`interpretation` - How the query string was interpreted. * :attr:`search_options` - Various search_options. * :attr:`result` - The search result. The :attr:`interpretation` is given as a list of dicts, each explaining how a part of the search key was interpreted (ie. what ASN attribute the search operation was performed on). The :attr:`result` is a list of dicts containing the search result. The smart search function tries to convert the query from a text string to a `query` dict which is passed to the :func:`search_asn` function. If multiple search keys are detected, they are combined with a logical AND. See the :func:`search_asn` function for an explanation of the `search_options` argument. This is the documentation of the internal backend function. It's exposed over XML-RPC, please also see the XML-RPC documentation for :py:func:`nipap.xmlrpc.NipapXMLRPC.smart_search_asn` for full understanding. """


        if search_options is None:
            search_options = {}

        self._logger.debug("smart_search_asn called; query_str: %s" % query_str)

        success, query = self._parse_asn_query(query_str)
        if not success:
            return {
                    'interpretation': query,
                    'search_options': search_options,
                    'result': [],
                    'error': True,
                    'error_message': 'query interpretaion failed'
            }

        if extra_query is not None:
            query = {
                'operator': 'and',
                'val1': query,
                'val2': extra_query
            }

        self._logger.debug("smart_search_asn; query expanded to: %s" % unicode(query))

        search_result = self.search_asn(auth, query, search_options)
        search_result['interpretation'] = query
        search_result['error'] = False

        return search_result