 
   @doc """
   Deletes the entries in the keyword list for a specific `key`.
+
   If the `key` does not exist, returns the keyword list unchanged.
-  Use `delete_first` to delete just the first entry in case of
+  Use `delete_first/2` to delete just the first entry in case of
   duplicated keys.
 
   ## Examples


  @doc """
  Fetches the value for a specific `key` and returns it in a tuple.
  If the `key` does not exist, returns `:error`.

  ## Examples

  end

  @doc """
  Updates the `key` with the given function. 
  
  If the `key` does not exist, raises `KeyError`.

  If there are duplicated keys, they are all removed and only the first one
  is updated.

  ## Examples
