Creates a parameter map which takes a tuple of the exchange 'from' and exchange 'to' codes 
        and returns the parameter name for that exchange

def create_parameter_map(self):
        """
        Creates a parameter map which takes a tuple of the exchange 'from' and exchange 'to' codes 
        and returns the parameter name for that exchange
        """
        names = self.modelInstance.names
        db = self.modelInstance.database['items']
        parameter_map = {}
        
        def get_names_index(my_thing):
            return[i for i, x in enumerate(names) if x == my_thing][0]
        
        for k, this_item in db.items():
            if this_item['type'] == 'process':
                production_id = [x['input'] for x in this_item['exchanges'] if x['type'] == 'production'][0]
                input_ids = [x['input'] for x in this_item['exchanges'] if x['type'] == 'technosphere']
                production_index = get_names_index(db[production_id]['name'])
                input_indexes = [get_names_index(db[x]['name']) for x in input_ids]
                parameter_ids = ['n_p_{}_{}'.format(x, production_index) for x in input_indexes]
                parameter_map_items = {(input_ids[n], k): parameter_ids[n] for n, x in enumerate(input_ids)}
                #check = [self.modelInstance.params[x]['description'] for x in parameter_ids]
                #print(check)
                #print(parameter_map_items)
                parameter_map.update(parameter_map_items)
                
        self.parameter_map = parameter_map