text: const shallowEqual = function(a, b) {
    // if both are undefined
    // or one or the other is undefined
    // they are not equal
    if ((!a && !b) || (!a && b) || (a && !b)) {
      return false;
    }
  
    // they are the same object and thus, equal
    if (a === b) {
      return true;
    }
  
    // sort keys so we can make sure they have
    // all the same keys later.
    const akeys = Object.keys(a).sort();
    const bkeys = Object.keys(b).sort();
  
    // different number of keys, not equal
    if (akeys.length !== bkeys.length) {
      return false;
    }
  
    for (let i = 0; i < akeys.length; i++) {
      const key = akeys[i];
  
      // different sorted keys, not equal
      if (key !== bkeys[i]) {
        return false;
      }
  
      // different values, not equal
      if (a[key] !== b[key]) {
        return false;
      }
    }
  
    return true;
  };
  
  export default shallowEqual;
  