This came up for fixes to svg-gradient() (less/less.js#3261). There are no automated visual regression tests, so it might be good to do so for functions that create visual assets. See: https://github.com/garris/BackstopJS

### Example
let unreachableProxy = "http://127.0.0.1:8888"
try:
  let client = newHttpClient(proxy=newProxy(unreachableProxy), timeout=1)
  var res = client.getContent("https://github.com")
  echo res
except:
  echo "Timed out"

Current Output

timeout variable is ignored, program stuck until default socket timeout will happen

Expected Output

Timed out a

We already have a specialized checked exponentiation when the base is a literal and exponent can only be known at compile time.

Implement the case where exponent is a literal and base is only known at compile time. Vyper already has this: vyperlang/vyper#2072

This is a follow-up to #4097 where we used an AtomicInteger as a poor-mans replacement for a Semaphore with tryAcquire (or maybe even drainPermits).

Should suppress --strict warnings.