1. Shebang line: Changed from #!/usr/bin/env python to #!/usr/bin/env python3

2. Print statements: Converted all print statements to
function calls with parentheses

3. String formatting: Used f-strings (Python 3.6+) for cleaner string formatting

4. subprocess.check_output: Updated error handling to use
stderr=subprocess.DEVNULL

5. Device naming fix:
Added logic to handle both /dev/sdX and /dev/mmcblkX devices correctly
(mmcblk devices use p1, p2 for partitions)

6. Better progress indication: Added dots while waiting for devices

7. Cleaner error messages: Improved error handling and messages

Issue-ID: 1

Signed-off-by: Chebanov Kostiantyn