 
   @doc """
   Determines the extension for an artifact based off its type.
-  Toolchains use xz compression
+  Toolchains use xz compression.
   """
   @spec ext(Nerves.Package.t) :: String.t
   def ext(%{type: :toolchain}), do: "tar.xz"

  end

  @doc """
  The full path to the artifact
  """
  @spec dir(Nerves.Package.t, Nerves.Package.t) :: String.t
  def dir(pkg, toolchain) do

  end

  @doc """
  Cleans the artifacts for the package providers of all packages.
  """
  @spec clean(Nerves.Package.t) :: :ok | {:error, term}
  def clean(pkg) do
