You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: my_classdata.m
    path of file: ./repos/bspm/thirdparty/spm12/toolbox/marsbar-0.44/@maroi/private
    
    the code of the file until where you have to start completion: function cdata = my_classdata(fieldname, value)
% my_classdata method - sets/gets class data

    
function cdata = my_classdata(fieldname, value)
% my_classdata method - sets/gets class data
% maroi class data is implemented with a persistent variable
% CLASSDATA  This is a structure containing fields
%
% spacebase  - space in which to do ROI combination 
% fileend