int list have no len()

[snippsat]

I try to write my list, but I need len() for write it.
if I write in str, they print 5 item.

Most be str to write paramiko doc.
Example if have list with integers,need to convent fourth and back to original list.

lst = [1, 2, 3 ,4]
# Most be string befor write
lst = ','.join(str(i) for i in lst)
with open('test.dat', 'w') as f:
    f.write(lst)

with open('test.dat') as f:
    lst = f.read().split(',')
    lst = [int(i) for i in lst]
    print(lst)

Output:
[1, 2, 3, 4]