    Resume job in foreground.
    
    Equivalent to the JOB_SPEC argument to the `fg' command.  Resume a
    stopped or background job.  JOB_SPEC can specify either a job name
    or a job number.  Following JOB_SPEC with a `&' places the job in
    the background, as if the job specification had been supplied as an
    argument to `bg'.
    
    Exit Status:
    Returns the status of the resumed job.
