private bool IsGhostedMultiplicationSign(IExpressionUnit currentExpressionUnit) { if (previousExpressionUnit == null) { return(false); } return(previousExpressionUnit.IsCloseBracket() && currentExpressionUnit.IsNumber() || previousExpressionUnit.IsCloseBracket() && currentExpressionUnit.IsOpenBracket() || previousExpressionUnit.IsNumber() && currentExpressionUnit.IsOpenBracket()); }