How can I fix this error?

[hoavutinh]

c:\Temp\mmdb-convert-master>mmdb-convert.py GeoLite2-City.mmdb > GeoIPCity.dat
Traceback (most recent call last):
File "C:\Temp\mmdb-convert-master\mmdb-convert.py", line 463, in
metadata, the_tree, _ = parse_mm_file(content)
File "C:\Temp\mmdb-convert-master\mmdb-convert.py", line 327, in parse_mm_file
tree = parse_search_tree(s[:tree_size], mm['record_size'].int_val())
File "C:\Temp\mmdb-convert-master\mmdb-convert.py", line 123, in parse_search_tree
left, right = to_leftright(s[p:p+record_bytes])
File "C:\Temp\mmdb-convert-master\mmdb-convert.py", line 80, in to_int28
a, b = unpack("!LL", s + b'\x00')
NameError: name 'unpack' is not defined

[meteozond]

from struct import unpack

I guess...