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: paint.m
    path of file: ./repos/ExploreASL/External/SPMmodified/@slover
    
    the code of the file until where you have to start completion: function obj = paint(obj, params)
% Method to display slice overlay
% FORMAT obj = paint(obj, params)
%
% Inputs
% obj         - slice overlay object

    
function obj = paint(obj, params)
% Method to display slice overlay
% FORMAT obj = paint(obj, params)
%
% Inputs
% obj         - slice overlay object
% params      - optional structure containing extra display parameters
%               - refreshf - overrides refreshf in object
%               - clf      - overrides clf in object
%               - userdata - if 0, does not add object to userdata field
%               (see below)
%
% Outputs
% obj         - which may have been filled with defaults
%
% paint attaches the object used for painting to the 'UserData' field of
% the figure handle, unless instructed not to with 0 in userdata flag
%__________________________________________________________________________

% Matthew Brett
% $Id: paint.m 6623 2015-12-03 18:38:08Z guillaume $

fig_struct_fields = {'Position', 'Units'};

if nargin < 2
    params = [];
end