Problems with pickle in python

import pickle


hello="hello"

pickle.dump(open('file.txt', 'wb'), hello)

print (hello)



hi=pickle.load(open('file.txt', 'rb'))

print (hi)

File "/home/ubuntu/workspace/tests.py", line 7, in <module>
    pickle.dump(open('file.txt', 'wb'), hello)
TypeError: file must have a 'write' attribute