How to download ERA5 data for the data in successive months but in two adjacent years

I couldn't find the script or approach to download the data with the attribute as I describe in the following:

1. one single file;
2. contains data in successive months in two adjacent years ( for example, from 20081201 to 20090201);

In cdsapi, when I use the function retrieve in Client class, I have to provide a request as a type of dictionary which contains the information such as 'variables', 'year', 'month', etc..

I don't know whether I can handle the year and month as 'year': /[2008, 2009], 'month':[[12],[1,2]]

or is there any other way I can retrieve the data without creating or using Client. retrieve function.