def to_list_of(self, state):<EOL>
if not self._is_kind(Fold):<EOL><INDENT>raise TypeError('<STR_LIT>')<EOL><DEDENT>pure = lambda a: Const([])<EOL>func = lambda a: Const([a])<EOL>return self.apply(func, pure, state).unwrap()<EOL>
Returns a list of all the foci within `state`.

        Requires kind Fold. This method will raise TypeError if the
        optic has no way to get any foci.