ImportError: bad magic number in 'rosbag': b'\x03\xf3\r\n'

edit

I am trying to run the python file called 'bag_parse.py' that imports rosbag package using the following command:

python bag_parse.py

My Python file is simple for testing:

import rosbag
bag = rosbag.Bag('scan_odom1.bag')
for topic, msg, t in bag.read_messages(topics=['/odom']):
    print(msg)
bag.close()

I get the following error:

ImportError: bad magic number in 'rosbag': b'\x03\xf3\r\n'

ROS distribution: Melodic