private static void add(final List<CharSequence> css, final CharSequence... csse) {
        if (css != null) {
            css.addAll(Arrays.asList(csse));
        }
    }
Evaluates both the double value and the CharSequence representation of this DegreeFormula
to allow for a more performant calculation.

@param varMap varmap to calculate values for
@return pair with calculated double value as first param (might be null) and text representation as secod (never null)
main/src/main/java/cgeo/geocaching/utils/formulas/DegreeFormula.java