   with no limitation and is not monotonic.
   """
   @spec os_time(time_unit) :: integer
+  @doc since: "1.3.0"
   def os_time(unit) do
     :os.system_time(normalize_time_unit(unit))
   end

  Inlined by the compiler.
  """
  @spec os_time() :: integer
  def os_time do
    :os.system_time()
  end

  Returns the number of schedulers in the VM.
  """
  @spec schedulers :: pos_integer
  @doc since: "1.3.0"
  def schedulers do
    :erlang.system_info(:schedulers)
  end
