 
   @doc """
   Reads many configuration files given by wildcard into a single config.
+
   Raises an error if `path` is a concrete filename (with no wildcards)
-  but the corresponding file does not exist.
+  but the corresponding file does not exist; if `path` matches no files,
+  no errors are raised.
   """
   def read_wildcard!(path) do
     paths = if String.contains?(path, ~w(* ? [ {))do

  end

  @doc ~S"""
  Imports configuration from the given file.

  The path is expected to be relative to the directory the
  current configuration file is on.

  ## Examples


  Persists the given configuration by modifying
  the configured applications environment.

  `config` should be a list of `{app, app_config}` tuples or a
  `%{app => app_config}` map where `app` are the applications to
  be configured and `app_config` are the configuration (as key-value
  pairs) for each of those applications.

  Returns the configured applications.

  ## Examples

      Mix.Config.persist(logger: [level: :error], my_app: [my_config: 1])
      #=> [:logger, :my_app]

  """
  def persist(config) do
    for {app, kw} <- config do
