markRenderFunction: Mark a function as a render function
In sheikhbarabas/shiny: Web Application Framework for R

Should be called by implementers of renderXXX functions in order to mark their return values as Shiny render functions, and to provide a hint to Shiny regarding what UI function is most commonly used with this type of render function. This can be used in R Markdown documents to create complete output widgets out of just the render function.

1	markRenderFunction(uiFunc, renderFunc, outputArgs = list())

`uiFunc`	A function that renders Shiny UI. Must take a single argument: an output ID.
`renderFunc`	A function that is suitable for assigning to a Shiny output slot.
`outputArgs`	A list of arguments to pass to the `uiFunc`. Render functions should include `outputArgs = list()` in their own parameter list, and pass through the value to `markRenderFunction`, to allow app authors to customize outputs. (Currently, this is only supported for dynamically generated UIs, such as those created by Shiny code snippets embedded in R Markdown documents).