- @api.multi - to get recordset in your method
- @api.one - to get browse_records one by one in your method
in above examples @api.multi is used, but @api.one also may be used to deal with ids, depending on requirements (However, it's strongly recommended to use @api.multi instead of @api.one for performance reasons).
Or if it's simple function that does not have to deal with records/ids then for python method choose decorator:
- @api.model - Allows to be polite with old style API.
- @api.multi - Again, you can use it here as well, just pass
References: Odoo RPC documentation, Odoo 8 API method decorators