     end
   end
 
+  # Removes all files and directories in the destination directory,
+  # excluding dotfiles so that git repository is not blown away.
   @spec clean_dest(binary) :: :ok
 
   defp clean_dest(dest) do
     File.mkdir_p! dest
     msg_mkdir dest
 
-    # exclude dotfiles so that git repository is not blown away
     dest
     |> File.ls!
     |> Enum.reject(&String.starts_with?(&1, "."))

    end
  end

  @spec check_tz() :: Error.result

  defp check_tz() do

    end
  end

  # Checks if the effective user have a write
  # permission on the destination directory.
  @spec check_dest_perm(binary) :: Error.result

  defp check_dest_perm(dest) do
