Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal lateral chest radiographs demonstrate no interval change in small left pneumothorax . Again seen is a nondisplaced fracture of left 7th rib . The visualized heart , mediastinal contour and hila are unremarkable . The lungs are notable for bibasilar atelectasis and are otherwise clear .
    OUTPUT:
    
1 . Unchanged small left pneumothorax . 2 . Nondisplaced left ___ posterior rib fracture better seen on prior sudy .