def GetItem(self, key):<EOL>
return self._compose_optic(optics.GetitemLens(key))<EOL>
A lens that focuses an item inside a container. Analogous to
        `operator.itemgetter`.

            >>> from lenses import lens
            >>> lens[0]
            UnboundLens(GetitemLens(0))
            >>> lens.GetItem(0)
            UnboundLens(GetitemLens(0))
            >>> lens[0].get()([1, 2, 3])
            1
            >>> lens['hello'].get()({'hello': 'world'})
            'world'
            >>> lens[0].set(4)([1, 2, 3])
            [4, 2, 3]
            >>> lens['hello'].set('universe')({'hello': 'world'})
            {'hello': 'universe'}