for i in file:
	hash_object = hashlib.sha256(i)
	hex_dig = hash_object.hexdigest()
	open('text.txt', 'a').write(hex_dig)

import time
t0=time.clock()
object = " "*256
f=open('text.txt', 'a')
for i in range(1000):
    f.write(object)
f.close()
t1=time.clock()
print(t1-t0)
>>> 0.00273258325833

import time
t0=time.clock()
object = " "*256
for i in range(1000):
    f=open('text.txt', 'a')
    f.write(object)
#    f.close()
t1=time.clock()
print(t1-t0)
>>> 0.081321350135