private TensorType inputType(TensorType givenType) {
        var builder = new TensorType.Builder(TensorType.Value.DOUBLE); // Any value type is permissible
        for (var d : givenType.dimensions())
            builder.dimension(d.size().isPresent() ? d.withSize(d.size().get() * 8) : d);
        return builder.build();
    }
Returns the type this requires when producing the given output type.
indexinglanguage/src/main/java/com/yahoo/vespa/indexinglanguage/expressions/PackBitsExpression.java