   def jaro_distance(_string, ""), do: 0.0
   def jaro_distance("", _string), do: 0.0
 
-  def jaro_distance(string1, string2) do
+  def jaro_distance(string1, string2) when is_binary(string1) and is_binary(string2) do
     {chars1, len1} = chars_and_length(string1)
     {chars2, len2} = chars_and_length(string2)
 


  def slice("", _.._), do: ""

  def slice(string, first..-1) when first >= 0 do
    case String.Unicode.split_at(string, first) do
      {_, nil} ->
        ""


  """
  @spec equivalent?(t, t) :: boolean
  def equivalent?(string1, string2) when is_binary(string1) and is_binary(string2) do
    normalize(string1, :nfd) == normalize(string2, :nfd)
  end

