presto-main/src/main/java/io/prestosql/metadata/PolymorphicScalarFunctionBuilder.java/PolymorphicScalarFunctionBuilder/concat
class PolymorphicScalarFunctionBuilder:    @SafeVarargs
    public static Function<SpecializeContext, List<Object>> concat(Function<SpecializeContext, List<Object>>... extraParametersFunctions)
    {
        return context -> {
            ImmutableList.Builder<Object> extraParametersBuilder = ImmutableList.builder();
            for (Function<SpecializeContext, List<Object>> extraParametersFunction : extraParametersFunctions) {
                extraParametersBuilder.addAll(extraParametersFunction.apply(context));
            }
            return extraParametersBuilder.build();
        };
    }