inputCode: flexibleAPI Add-on

function inputCode(x, y, mask)
    local num = ui.new() -- Creates
    local numpad = num:addButton('numpad', 0, 1, {' 987 ',' 654',' 321',' X0V'})
    local screen = num:addLabel('screen', 0,0, '     ')
    numpad:setAction('input')
    num:setCommonAttribute({name = ''},{cont = 'num_origin'})
    numpad:setColors(colors.lime, colors.lightBlue)
    screen:setColors(colors.white, colors.blue)
    num:addPoint('num_origin', x, y)
    local length = screen.text:len()
    local current = ''
    while true do
        num:draw()
        local _, m, x, y = os.pullEvent('mouse_click')
        click = num:mouse({x,y})
        if click then
            if click[1][1] == 'input' then
                local text = num.ui[click[1][2]].text
                local xx, yy = unpack(click[1][3])
                local single = string.sub(text[yy],xx,xx)
                if single ~= 'V' and single ~= 'X' and single ~= ' ' and current:len() ~= length then
                    current = current..single
                    if not(mask) then
                        screen.text = current..string.rep(' ', length - current:len())
                    else
                        screen.text = string.rep(mask:sub(1,1),current:len())..string.rep(' ', length - current:len())
                    end

                elseif single == 'V' then
                    return current
                elseif single == 'X' then
                    return nil
                end
            end
        end
    end
end