default <A> Stream<Meta<A, String>> metaOn(Collection<A> models) {
        return models.stream().flatMap(this::metaOn);
    }
Renders all the specified models into a stream of code models. This is
used internally to provide the other interface methods.

@param <A>     the input type
@param models  the models to generate
@return        a stream of meta objects

@see Meta
common-parent/codegen/src/main/java/com/speedment/common/codegen/Generator.java