function parseBody(buffer, callback) {
  zlib
    .unzip(buffer, (error, body) => {
      try {
        callback(error, JSON.parse(body.toString()));
      } catch (error) {
        callback(error);
      }
    });
}
Parse the buffer, StackExchange promises to always deliver zipped content,
but since JSON parsing is required just wrap it in a try/catch.

@param {Buffer} buffer response content
@param {Function} callback return results
@api private