question: public static String removeChars ( String str , String oldchars ) { int pos = indexOfChars ( str , oldchars ) ; if ( pos == - 1 ) { return str ; } StringBuilder buf = new StringBuilder ( ) ; int start = 0 ; do { buf . append ( str . substring ( start , pos ) ) ; start = pos + 1 ; pos = indexOfChars ( str , oldchars , start ) ; } while ( pos != - 1 ) ; if ( start < str . length ( ) ) { buf . append ( str . substring ( start ) ) ; } return buf . toString ( ) ; }
target:  Remove any occurrances of 'oldchars' in 'str'. Example: removeChars("Hello, world!", ",!") returns "Hello world"