       iex> add_attribute("tag tag=2", "attr=1")
       "tag attr=1 tag=2"
   """
+  @spec add_attribute(String.t(), String.t()) :: String.t()
   def add_attribute(tag, attribute) do
     String.replace(tag, tag_name(tag), "#{tag_name(tag)} #{attribute}", global: false)
   end

      iex> deep_reverse [1, [2, 3], 4]
      [4, [3, 2], 1]
  """
  def deep_reverse(list) do
    list |> Enum.reverse()
    |> Enum.map(fn

      iex> find_attribute("tag attrx = 1 attr = '2' attra= 4 ", "attr = 3")
      "attr='2'"
  """
  @spec find_attribute(String.t(), String.t()) :: String.t() | nil
  def find_attribute(tag, attr) do
    [attr_name | _] =
      attr
