# -*- coding: utf-8 -*-
import io
import os
import hashlib

s = u' '*(256**4//2)  #+ u"перфекто"
s=s.encode('utf-8')
#s=' '*(10)

in_digest = hashlib.md5(s).hexdigest()
fname = 'outlong.dat'

if os.path.exists(fname):
    os.unlink(fname)

with io.FileIO(fname, 'wb') as f:
#with open(fname, 'wb') as f:
     n = f.write(s)

#n = os.stat(fname).st_size
print("Written %d out of %d" % (n, len(s)))
if n != len(s):
    print("%d bytes were not written" % (len(s) - n))

# checksum
with open(fname, 'rb') as f:
    out_digest = hashlib.md5(f.read()).hexdigest()
assert in_digest == out_digest, "Digests do not match"
print("all ok")