Hash function in python

[hamedpersian]

Hi guys. I'm new to cryptography. I'm practicing different hash algorithm. IS there any one who can tell me how to write a simple hash function that creates a 32-bit hash of a file?
Thanks.

[Rabbit]

A simple way would be to loop through the input 4 bytes at a time and xor it into a base.

[hamedpersian]

In the first part that i wrote there is some error. It get the input from the user and convert it to binary. It works but at the end it gives me an error regarding the value for the base 16. I copying my code here, please tell me where the error is coming from.
thanks.

----------------------------------

import BitVector
import io

if __name__ == "__main__":
    message = raw_input("your message:")
    f = open('file.dat','w')
    f.write(message)
    f.close()
    
    f = open('file.dat')
    while 1:
        rr = f.readline(1)
        hex = rr.encode("hex")
        bits = bin(int(hex, 16))[2:]
        print bits
        if not rr:break
    f.close()