PropCheck.timeout

You're seeing just the macro timeout, go back to PropCheck module for more information.
Link to this macro

timeout(time_limit, prop)

View Source (macro)

Signifies that prop should be considered failing if it takes more than time_limit milliseconds to return.

The purpose of this wrapper is to test code that may hang if something goes wrong. timeout cannot contain any more wrappers.

iex> use PropCheck
iex> quickcheck(
...>   timeout(100, forall n <- nat() do
...>     :ok == :timer.sleep(n*100)
...>   end)
...> )
false