   @doc """
   Replaces prefix in `string` by `replacement` if it matches `match`.
 
-  Returns the string untouched if there is no match.
+  Returns the string untouched if there is no match. If `match` is an empty
+  string (`""`), `replacement` is just prepended to `string`.
 
   ## Examples
 

  @doc """
  Replaces suffix in `string` by `replacement` if it matches `match`.

  Returns the string untouched if there is no match.

  ## Examples


      "hello mundo"
      iex> String.replace_suffix("hello world world", " world", " mundo")
      "hello world mundo"

      iex> String.replace_suffix("hello", "", " world")
      "hello world"

  """
  @spec replace_suffix(t, t, t) :: t
