Zlib decompress file, producing file.out

zunzip.py

#!/usr/bin/env python
import zlib, sys

if len(sys.argv) != 2:
    print "Usage: %s <zlib-compressed-file>"%sys.argv[0]
    print "Produces decompressed file with \".out\" filename suffix."
    sys.exit(0)

indata=open(sys.argv[1], "rb").read()
outdata=zlib.decompress(indata)
with open(sys.argv[1] + ".out", "wb") as f:
    f.write(outdata)
    f.close()
    

Traceback (most recent call last):
File "./zunzip.py", line 10, in
outdata=zlib.decompress(indata)
zlib.error: Error -3 while decompressing data: incorrect data check