[capink]

does the below template do what you want?

program:
    f = field('#taglike');
    icons = '';
    sep = ':';
    for keyword in 'foo,bar,test':
        val = contains(f, keyword, strcat(keyword, '.png'), '');
        if val then
            icons = list_union(icons, val, sep)
        fi
    rof;
    ifempty(icons, 'unknown.png')