Adding plot interactively

I am plotting a variable for different country. I can chose the country interactively using the Select function. Now I would like to have the possibility to add curve one by one and not erasing each time the previous plot. Is there any example which I can used ?
By example thank you.
Below the piece of my code where I am selecting the country

    var c = cb_obj.value;
    var y =[c];['cases'] = y;
    callback = CustomJS(args=dict(s1=source,s2=src,y_range=myfig.y_range,ax=myfig.yaxis[0]), code=code)
    select_countries = Select(title="Country:", value='France', options=CountriesEU)
    select_countries.js_on_change('value', callback)

Hi @odadoun please edit your post to use code formatting so that the code is intelligible (either with the </> icon on the editing toolbar, or triple backtick ``` fences around the code blocks)