function process(obj) {
  const mqKeys = [];

  // copy non-media-query stuff
  const res = Object.keys(obj).reduce((res, key) => {
    if (!isMediaQuery(key)) {
      res[key] = obj[key];
    } else {
      mqKeys.push(key);
    }
    return res;
  }, {});

  // apply media query stuff
  if (mqKeys.length) {
    const matchObject = getMatchObject();
    mqKeys.forEach(key => {
      const mqStr = key.replace(PREFIX, '');
      const isMatch = mediaQuery.match(mqStr, matchObject);
      if (isMatch) {
        merge(res, obj[key]);
      }
    });
  }

  return res;
}
Process and apply media queries in object
@param {Object} obj
@returns {null|Object}