Blazor RenderTreeBuilder access event function onkeyup

I am dynamically building an input box via the RenderTreeBuilder in a class called "RenderForm".

I want to fire a function that exists in my IndexBase.cs page "onkeyup" but I am unsure how I reference the function as RenderForm cannot see the function.

It's supposed to be something like this:

builder.AddAttribute(2, "onkeyup", 
EventCallback.Factory.Create<Microsoft.AspNetCore.Components.Web.KeyboardEventArgs>(this, 
IndexBase.MyFunction));