[Errno 16] Resource busy: '/dev/disk0'

Sviatoslavs-MacBook-Pro:~ MrMustard$ cd Desktop/
Sviatoslavs-MacBook-Pro:Desktop MrMustard$ chmod +x gpt_surgeon.py
Sviatoslavs-MacBook-Pro:Desktop MrMustard$ sudo ./gpt_surgeon.py repair /dev/disk0 4
Password:

Read MBR and GPT from /dev/disk0.
Changing type of partition #4 on /dev/disk0 to HFS+...
Traceback (most recent call last):
  File "./gpt_surgeon.py", line 216, in <module>
    main()
  File "./gpt_surgeon.py", line 211, in main
    fixGPTPartitionType(diskDevice, selectedPartition)
  File "./gpt_surgeon.py", line 153, in fixGPTPartitionType
    disk = open(diskDevice, 'wb')
IOError: [Errno 16] Resource busy: '/dev/disk0'
Sviatoslavs-MacBook-Pro:Desktop MrMustard$ sudo diskutil unmountDisk /dev/disk0
Unmount of all volumes on disk0 was successful
Sviatoslavs-MacBook-Pro:Desktop MrMustard$ sudo ./gpt_surgeon.py repair /dev/disk0 4

Read MBR and GPT from /dev/disk0.
Changing type of partition #4 on /dev/disk0 to HFS+...
Traceback (most recent call last):
  File "./gpt_surgeon.py", line 216, in <module>
    main()
  File "./gpt_surgeon.py", line 211, in main
    fixGPTPartitionType(diskDevice, selectedPartition)
  File "./gpt_surgeon.py", line 153, in fixGPTPartitionType
    disk = open(diskDevice, 'wb')
IOError: [Errno 16] Resource busy: '/dev/disk0'

I can not seem to get through this part, please if anyone can help me I would appreciate it.