question: public void addOperand ( int startTick , int endTick ) { if ( operands . size ( ) == 0 && this . startTick != startTick ) { throw new IllegalArgumentException ( "The start tick of the first operand must be equal to the start tick of the combined fragment" ) ; } operands . add ( new Operand ( startTick , endTick ) ) ; }
target:  Adds an operand to the combined fragement.