How to use the boto.s3.key.Key function in boto

def diagnose(self, key):
    k = boto.s3.key.Key(self.s3_bucket)
    k.key = key
    log_text_gz = k.get_contents_as_string()
    log_text = gzip.GzipFile(fileobj=StringIO(log_text_gz)).read().decode('utf-8')
    summary = parse_test_failure.extract_failure_summary(log_text)
    if not summary:
      summary = "Unable to diagnose"
    template = Template("""
      <h1>Diagnosed failure</h1>
      <code><pre>{{ summary|e }}</pre></code>
      <h1>Full log</h1>
      <code><pre>{{ log_text|e }}</pre></code>
    """)
    return self.render_container(template.render(summary=summary, log_text=log_text))

z.write(filename)

        try:
            aws_id = settings.AWS_ID
            aws_key = settings.AWS_KEY
            aws_bucket_name = settings.AWS_BACKUP_BUCKET_NAME
        except:
            print 'Please configure AWS credentials in settings/local.py!'
            return

        conn = boto.connect_s3(aws_id, aws_key)
        buckets = conn.get_all_buckets()

        for bucket in buckets:
            if bucket.name == aws_bucket_name:
                k = Key(bucket)
                k.key = filename_zip
                k.set_contents_from_filename(filename_zip)
                break

        call(['rm', filename])
        call(['rm', filename_zip])

def put_obj_acl(conn, opts):
    print "uploading object ACL to bucket: '%s', object name: '%s'" \
        % (opts.bucket_name, opts.obj_name)
    bucket = conn.get_bucket(opts.bucket_name)
    k = Key(bucket)
    k.key = opts.obj_name
    f = open(opts.putacl_file, "r")
    try:
        xml = f.read()
    finally:
        f.close()
    k.set_xml_acl(xml)
    return 0

def open_s3(self):
        """
        Opens connection to S3 returning bucket and key
        """
        conn = boto.connect_s3(self.AWS_ACCESS_KEY_ID, self.AWS_SECRET_ACCESS_KEY)
        try:
            bucket = conn.get_bucket(self.AWS_STORAGE_BUCKET_NAME)
        except boto.exception.S3ResponseError:
            bucket = conn.create_bucket(self.AWS_STORAGE_BUCKET_NAME)
        return bucket, boto.s3.key.Key(bucket)

def upload_to_S3(bucket, key, file_object):
    """
    Uploads a file object to a S3 instance

    Inputs: ::\n
        bucket: S3 bucket we want to upload to
        key: the key to access the file in the bucket;
        file_object: the file that needs to be uploaded

    """
    k = Key(bucket)
    k.key = key
    k.set_contents_from_file(file_object)
    k.set_acl('public-read')
    return k.generate_url(expires_in=0, query_auth=False, force_http=True)

def s3_url(user_id, filename, kq_id):
    conn = boto.connect_s3(settings.AWS_ACCESS_KEY_ID, settings.AWS_SECRET_ACCESS_KEY)
    bucket = conn.get_bucket(settings.AWS_STORAGE_BUCKET_NAME)
    k = boto.s3.key.Key(bucket)
    name = "%d/%s/%s" % (user_id, kq_id, filename)
    k.key = name
    return k.generate_url(expires_in=0, query_auth=False)

def deploy_json_data(s3_buckets):

    TUMBLR_FILENAME = app_config.TUMBLR_FILENAME

    with open(TUMBLR_FILENAME, 'r') as json_output:
        with gzip.open(TUMBLR_FILENAME + '.gz', 'wb') as f:
            f.write(json_output.read())

    for bucket in s3_buckets:
        conn = boto.connect_s3()
        bucket = conn.get_bucket(bucket)
        key = boto.s3.key.Key(bucket)
        key.key = '%s/live-data/%s-data.json' % (app_config.PROJECT_SLUG, app_config.PROJECT_SLUG)
        key.set_contents_from_filename(
            TUMBLR_FILENAME + '.gz',
            policy='public-read',
            headers={
                'Cache-Control': 'max-age=5 no-cache no-store must-revalidate',
                'Content-Encoding': 'gzip'
            }
        )

    os.remove(TUMBLR_FILENAME + '.gz')

def download(self, keyname):
        k = Key(self.bucket)
        k.key = keyname

        encrypted_out = tempfile.TemporaryFile()
        k.get_contents_to_file(encrypted_out)
        encrypted_out.seek(0)

        return encrypted_out

def open_s3(self):
        """
        Opens connection to S3 returning bucket and key
        """
        conn = boto.connect_s3(self.AWS_ACCESS_KEY_ID, self.AWS_SECRET_ACCESS_KEY)
        try:
            bucket = conn.get_bucket(self.AWS_BUCKET_NAME)
        except boto.exception.S3ResponseError:
            bucket = conn.create_bucket(self.AWS_BUCKET_NAME)
        return bucket, boto.s3.key.Key(bucket)