Vim. Close the quicklist and return to the original window

I'd like to write a function that toggles the quicklist and when closing it, it returns to the window it was in before the quicklist opening. I tried to improve some function I found but it does not work as expected:

function! ToggleQuickFix()
    if empty(filter(getwininfo(), 'v:val.quickfix'))
        copen 20
    else
        call feedkeys("^W^P")
        cclose
    endif
endfunction