def all_combinations_for_elements(self, element_symbols):
        """
        Return a list with all the the possible combination of pseudos
        for the given list of element_symbols.
        Each item is a list of pseudopotential objects.

        Example::

            table.all_combinations_for_elements(["Li", "F"])
        """
        d = OrderedDict()
        for symbol in element_symbols:
            d[symbol] = self.select_symbols(symbol, ret_list=True)

        from itertools import product
        return list(product(*d.values()))