def _generate_key(self, filename, headers=None):
        if self.base_dir:
            filename = '%s/%s' % (self.base_dir, filename)

        k = self.bucket.new_key(filename)
        if not headers or headers not in 'Content-Type':
            ct = mimetypes.guess_type(filename)[0]
            if ct:
                k.set_metadata('Content-Type', ct)

        return k
dataset/ETHPy150Open lepture/flask-storage/flask_storage/s3.py/S3Storage._generate_key/swapped operands of `not in`