Nothing
n <- 1
python <- Sys.which("python")
if(!nzchar(python))
python <- Sys.which("python3")
res <- system2(python,
c("-c", shQuote(sprintf("print(%i+1)", n))), stdout = TRUE)
stopifnot(identical(res, as.character(n + 1)))
Any scripts or data that you put into this service are public.
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.