def __getitem__(self, key):
        """Retrieve a field from the layout.

        Returns
        -------
        :class:`Field`
            The field associated with :py:`key`.

        Raises
        ------
        KeyError
            If there is no field associated with :py:`key`.
        """
Retrieve a field from the layout.

        Returns
        -------
        :class:`Field`
            The field associated with :py:`key`.

        Raises
        ------
        KeyError
            If there is no field associated with :py:`key`.
        
amaranth/lib/data.py