   end
 
   @doc """
-  Fetches the value for specific key. If key does not exist,
-  an error is raised.
+  Fetches the value for specific `key`. If `key` does not exist,
+  a `KeyError` is raised.
 
   ## Examples
 

  end

  @doc """
  Returns all values.

  ## Examples


  end

  @doc """
  Gets the value for a specific `key`.

  If `key` does not exist, return default value (`nil` if no default value).

  If duplicated entries exist, the first one is returned.
  Use `get_values/2` to retrieve all entries.

  ## Examples

