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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 search_prefix(self):
 """ Search prefixes. Does not yet incorporate all the functions of the search_prefix API function due to difficulties with transferring a complete 'dict-to-sql' encoded data structure. Instead, a list of prefix attributes can be given which will be matched with the 'equals' operator if notheing else is specified. If multiple attributes are given, they will be combined with the 'and' operator. Currently, it is not possible to specify different operators for different attributes. """


        # extract operator
        if 'operator' in request.json:
            operator = request.json['operator']
        else:
            operator = 'equals'

        # fetch attributes from request.json
        attr = XhrController.extract_prefix_attr(request.json)

        # build query dict
        n = 0
        q = {}
        for key, val in attr.items():
            if n == 0:
                q = {
                    'operator': operator,
                    'val1': key,
                    'val2': val
                }
            else:
                q = {
                    'operator': 'and',
                    'val1': {
                        'operator': operator,
                        'val1': key,
                        'val2': val
                    },
                    'val2': q
                }
            n += 1

        # extract search options
        search_opts = {}
        if 'children_depth' in request.json:
            search_opts['children_depth'] = request.json['children_depth']
        if 'parents_depth' in request.json:
            search_opts['parents_depth'] = request.json['parents_depth']
        if 'include_neighbors' in request.json:
            search_opts['include_neighbors'] = request.json['include_neighbors']
        if 'max_result' in request.json:
            search_opts['max_result'] = request.json['max_result']
        if 'offset' in request.json:
            search_opts['offset'] = request.json['offset']

        try:
            result = Prefix.search(q, search_opts)
        except NipapError, e:
            return json.dumps({'error': 1, 'message': e.args, 'type': type(e).__name__})

        return json.dumps(result, cls=NipapJSONEncoder)