question: public int incr ( T k , int delta ) { Integer i = counts . get ( k ) ; if ( i == null ) { i = 0 ; } int next = i . intValue ( ) + delta ; if ( next < 0 ) { throw new java . lang . ArithmeticException ( ) ; } if ( next == 0 ) { counts . remove ( k ) ; } else { counts . put ( k , i + delta ) ; } return i ; }
target:  Adds delta to the count for k and returns the count prior to addition. 