     for file <- files do
       output_path
       |> Path.join(file)
-      |> File.rm
+      |> File.rm()
 
       output_path
       |> Path.join("#{file}.gz")
-      |> File.rm
+      |> File.rm()
     end
   end
 

  @moduledoc false

  @doc """
  Digests and compresses the static files and saves them in the given output path.

    * `input_path` - The path where the assets are located
    * `output_path` - The path where the compiled/compressed files will be saved
  """
  @spec compile(String.t, String.t) :: :ok | {:error, :invalid_path}
  def compile(input_path, output_path) do

  end

  @doc """
  Deletes compiled/compressed asset files that are no longer in use based on
  the specified criteria.

  ## Arguments

    * `path` - The path where the compiled/compressed files are saved
    * `age` - The max age of assets to keep in seconds
    * `keep` - The number of old versions to keep

  """
  @spec clean(String.t, integer, integer, integer) :: :ok | {:error, :invalid_path}
  def clean(path, age, keep, now \\ now()) do
    if File.exists?(path) do
      manifest = load_manifest(path)
      files = files_to_clean(manifest, now - age, keep)
      remove_files(files, path)
      remove_files_from_manifest(manifest, files, path)
      :ok
    else
      {:error, :invalid_path}
