question: private static String nextGraphFileName ( Body b , String baseName ) throws java . io . IOException { File dir = makeDirectoryIfMissing ( b ) ; final String prefix = dir . toString ( ) + File . separatorChar + baseName ; File file = null ; int fileNumber = 0 ; do { file = new File ( prefix + fileNumber + DotGraph . DOT_EXTENSION ) ; fileNumber ++ ; } while ( file . exists ( ) ) ; return file . toString ( ) ; }
target:  Returns the next available name for a graph file.