python zip error

zipfile.py

# iterate through the list on messages
for number in message_number[0].split():

    # fetch the current message
    typ, data = connection.fetch(number, '(RFC822)')

    # parse the email
    message = email.message_from_string(data[0][1])

    # for each attachment
    for part in message.walk():
        attach_name = part.get_filename()
        print ("found %s" % attach_name)

        if attach_name:
            # extract the attachment from the email
            attach_dest = "/tmp/google_dmarc_report.zip"
            print("detaching into %s" % attach_dest)
            fd = file(attach_dest, "wb")
            attach_data = email.base64mime.decode(part.get_payload())
            fd.write(attach_data)
            fd.close

            # unzip
            print("unzipping %s" % attach_dest)
            zf = zipfile.ZipFile(attach_dest, 'r')
            zf.extractall("/tmp/")
            zf.close()

julienv@mac:~/Code/dmarc-parser [master -]$ python unzip.py 
unzipping /tmp/google_dmarc_report.zip

julienv@mac:~/Code/dmarc-parser [master -]$ cat unzip.py 
#!/usr/bin/env python
import zipfile
attach_dest = "/tmp/google_dmarc_report.zip"
# unzip
print("unzipping %s" % attach_dest)
zf = zipfile.ZipFile(attach_dest, 'r')
zf.extractall("/tmp/")
zf.close()