AttributeError: 'module' object has no attribute 'Bag'

edit

Program:

import time, sys, os
from ros import rosbag
import roslib, rospy
roslib.load_manifest('sensor_msgs')
from sensor_msgs.msg import Image

from cv_bridge import CvBridge
import cv2

TOPIC = 'camera/image_raw'
videopath='/Home/'
bagname='output1.bag'
def CreateVideoBag(videopath, bagname):
    '''Creates a bag file with a video file'''
    bag = rosbag.Bag(bagname, 'w')
    cap = cv2.VideoCapture(videopath)
    cb = CvBridge()
    prop_fps = cap.get(cv2.cv.CV_CAP_PROP_FPS)
    if prop_fps != prop_fps or prop_fps <= 1e-2:
        print ("Warning: can't get FPS. Assuming 24.")
        prop_fps = 24
    ret = True
    frame_id = 0
    while(ret):
        ret, frame = cap.read()
        if not ret:
            break
        stamp = rospy.rostime.Time.from_sec(float(frame_id) / prop_fps)
        frame_id += 1
        image = cb.cv2_to_imgmsg(frame, encoding='bgr8')
        image.header.stamp = stamp
        image.header.frame_id = "camera"
        bag.write(TOPIC, image, stamp)
    cap.release()
    bag.close()

if __name__ == "__main__":
    if len( sys.argv ) == 1:
        CreateVideoBag(videopath,bagname)
    else:
        print( "Usage: video2bag videofilename bagfilename")
bag.close()

Error output

$ python video2bag.py 
Error:
Traceback (most recent call last):
  File "video2bag.py", line 39, in <module>
    CreateVideoBag(videopath,bagname)
  File "video2bag.py", line 15, in CreateVideoBag
    bag = rosbag.Bag(bagname, 'w')
AttributeError: 'module' object has no attribute 'Bag'

Please help me with above error

Edit:

$ dpkg -l | grep rosbag
ii  ros-kinetic-rosbag                           1.12.14-0xenial-20180824-103606-0800                  amd64        This is a set of tools for recording from and playing back to ROS topics.
ii  ros-kinetic-rosbag-migration-rule            1.0.0-0xenial-20180809-134558-0800                    amd64        This empty package allows to export rosbag migration rule files without depending on rosbag.
ii  ros-kinetic-rosbag-storage                   1.12.14-0xenial-20180824-085858-0800                  amd64        This is a set of tools for recording from and playing back ROS message without relying on the ROS client library.