Apex job runner class to recursively execute scheduled job ever "n" minutes

JobRunner.cls

global without sharing class JobRunner implements Schedulable {
    Integer intervalMinutes;
    public JobRunner(Integer intervalMinutes) {
        this.intervalMinutes = intervalMinutes;
    }
    public void execute(SchedulableContext sc) {
        // Re-schedule ourself to run again in "intervalMinutes" time
        DateTime now  = DateTime.now();
        DateTime nextRunTime = now.addMinutes(intervalMinutes);
        String cronString = '' + nextRunTime.second() + ' ' + nextRunTime.minute() + ' ' + 
            nextRunTime.hour() + ' ' + nextRunTime.day() + ' ' + 
            nextRunTime.month() + ' ? ' + nextRunTime.year(); 
        System.schedule(JobRunner.class.getName() + '-' + now.format(), cronString, new JobRunner(intervalMinutes));
        // Abort the current job
        Id jobId = sc.getTriggerId();
        System.abortJob(jobId);     
        // Launch a batch job or call a future method to do the actual work
        Database.executeBatch(new SomeBatchJob());
    }
}

why are we aborting job on line 16?

@nitish771,
In this case, it's an example of being able to execute a scheduled apex job every n-minutes or even more frequently (although because SC is executed on a message queue, you should never execute less than a minute...) by calling a job (batch apex, in this case) and dynamically rescheduling a new instance of a scheduled job at a specific time. That's the only way to get scheduled execution every n-minutes without using multiple scheduled apex jobs.