How do you get process receipt to do what the developer product does?

I can't figure out what I should do to make the developer product table work

[1] = function(receipt, player)
    if player.Character and player.Character:FindFirstChild("Humanoid") then
        player.Character.Humanoid.Health = 0
        -- Indicate a successful purchase
        return true
    end
end
}


MarketplaceService.ProcessReceipt = function(ReceiptInformation)

    local player = Players:GetPlayerByUserId(ReceiptInformation.PlayerId)
    if not player then
        return Enum.ProductPurchaseDecision.NotProcessedYet
    end


    local handler = productFunctions[ReceiptInformation.ProductId]


    return Enum.ProductPurchaseDecision.PurchaseGranted

end

Is there like a function to trigger one of the developer products?

I have no idea how