Difference Between 2 files

[Gribouillis]

Simply use filter()

import difflib
import io

f_new = io.StringIO('''\
1
2
3
5
6
7
''')

f_old = io.StringIO('''\
1
2
3
4
5
6
''')

def my_ndiff(*args):
    return filter(lambda x: not x.startswith(' '), difflib.ndiff(*args))

if __name__ == '__main__':
    diff = my_ndiff(f_old.readlines(), f_new.readlines())
    print(''.join(diff))

Output:
- 4
+ 7