def set(self, newvalue):<EOL>
def setter(state):<EOL><INDENT>return self._optic.set(state, newvalue)<EOL><DEDENT>return setter<EOL>
Set the focus to `newvalue`.

            >>> from lenses import lens
            >>> set_item_one_to_four = lens[1].set(4)
            >>> set_item_one_to_four([1, 2, 3])
            [1, 4, 3]