question: private String compute ( String left , double right , boolean isInteger ) { if ( left == null && Double . isNaN ( right ) ) { return null ; } if ( isInteger && right == ( int ) right ) { return ( left == null ? "" : left ) + ( int ) right ; } else if ( Double . isInfinite ( right ) ) { return ( left == null ? "" : left ) + Tools . formatNumber ( right ) ; } else { return ( left == null ? "" : left ) + ( Double . isNaN ( right ) ? "" : right ) ; } }
target:  Adds a String and a double. If the double represents an integer tries to add it without trailing '.0'. If both are missing, then the result is missing; if one is missing, it is ignored. If the double is infinite, formats is using a symbol.