rename all files to their hash

import os, sys, hashlib

def main():
    thisdir = os.listdir(os.getcwd())
    thisfile = os.path.split(sys.argv[0])[1]
    files = [i for i in thisdir if i != thisfile]
    for file in files:

        filehash = hashlib.md5(open(file, "rb").read()).hexdigest()
        extension = os.path.splitext(file)[1]
        os.rename(file, filehash+extension)

        del(filehash)
        del(extension) #memory

if __name__ == "__main__":
    main()