I know it is possible to estimate the time it takes to complete a function (e.g., with sys.time(), but is there a way to benchmark a function and see which element within the function takes the longest/shortest?

So for example, given the code below, I should be able to performance test the function and determine for run 1, function_long is a bottleneck but for run 2, function_custom is the issue.

function_short <- function(){
  Sys.sleep(2)
}

function_long <- function(){
  sys.sleep(8)
}

function_custom <- function(x){
  sys.sleep(x)
}

function_to_test <- function(x){
  print("Starting function")
  
  print("2 second rest..")
  function_short()
  
  print("8 second rest..")
  function_long()
  
  print(paste0(x), " second rest..")
  function_custom(x)
}

# test these
## run 1
function_to_test(1)

## run 2
function_to_test(10)