<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def list_snapshots_for_a_minute(path, cam_id, day, hourm):
 """Returns a list of screenshots"""

    screenshoots_path = path+"/"+str(cam_id)+"/"+day+"/"+hourm
    if os.path.exists(screenshoots_path):
        screenshots = [scr for scr in sorted(os.listdir(screenshoots_path))]
        return screenshots
    else:
        return []