   @doc """
   Returns the value for `key` in `app`'s environment in a tuple.
 
-  If the specified application is not loaded, or the configuration parameter
-  does not exist, the function returns `:error`.
+  If the configuration parameter does not exist, the function returns `:error`.
   """
   @spec fetch_env(app, key) :: {:ok, value} | :error
   def fetch_env(app, key) do

  @doc """
  Returns the value for `key` in `app`'s environment.

  If the specified application is not loaded, or the configuration parameter
  does not exist, the function returns the `default` value.
  """
  @spec get_env(app, key, value) :: value
  def get_env(app, key, default \\ nil) do

  @doc """
  Returns the value for `key` in `app`'s environment.

  If the configuration parameter does not exist, raises `ArgumentError`.
  """
  @spec fetch_env!(app, key) :: value | no_return
  def fetch_env!(app, key) do
