>>> from phone import ncalls2

>>> v1 = ['934780245', '012', '618776611', '972399700', '11811',
...    '972399700', '012', '938765454', '012', '11811', '012', '11811']
>>> with open ('calls.txt', 'w') as f:
...    for e in v1:
...        a = f.write (e + '\n')
>>> ncalls2('calls.txt', 'result.txt')
>>> with open('result.txt', 'r') as f:
...     a = f.read()
>>> a
'012 4\n11811 3\n'