code: function _splitKey(key) {
    var insideBraces = false;
    var currentWord = '';
    var keys = [];
    for (var i = 0; i < key.length; i++) {
      currentWord += key[i];
      if (key[i] === '{') {
        insideBraces = true;
        continue;
      }
      if (key[i] === '}') {
        insideBraces = false;
        continue;
      }
      if (key[i] === '.' && !insideBraces) {
        keys.push(currentWord.slice(0, -1));
        currentWord = '';
      }
    }
    keys.push(currentWord);
    return keys;
  }
docs: Split string by '.' ignoring dots inside braces '{...}'
  Example1:
  <pre>
  var key = 'a.b.c';
  var keys = _splitKey(key);
  console.log(keys); // ['a', 'b', 'c']
  </pre>
  Example2:
  <pre>
  var key = 'a.{b.c}.d';
  var keys = _splitKey(key);
  console.log(keys); // ['a', '{b.c}', 'd']
  </pre>
  
  @param {string} key
  @returns {string[]}
  @private