How can a double tap be detected?

I've tried multiple scenarios. What I am trying to do is allow a basic function to fire when You double tap "A", but I can't seem to do it. I assume the problem is that input2 is already being set as "A" when I first press it because pressing it for the second time in the game means that every time you press it hence it will fire the function.

bool = true
locplay = game.Players.LocalPlayer
human = locplay.Character.Humanoid
game:GetService("UserInputService").InputBegan:connect(function(input1)
    if input1.KeyCode == Enum.KeyCode.A then
    local bool = false
        wait(.02)
        if bool == false then
            game:GetService("UserInputService").InputBegan:connect(function(input2)
                if input2.KeyCode == Enum.KeyCode.A then
                local bool = true
                    if bool == true then
                        human.WalkSpeed = 50
                        wait(.25)
                        human.WalkSpeed = 16
                    end
                end
            end)
        end
    end
end)
bool = false