code: function _addToTree(tree, branchToken, leafToken) {
    /* eslint-disable max-len, no-param-reassign */
    const leafValue = Utils.merge(tree[branchToken].fields[leafToken] || {}, _parseLeafToken(leafToken));
    tree[branchToken].fields[leafToken] = leafValue;
    /* eslint-enable max-len, no-param-reassign */
  
    return tree;
  }
docs: @private
  
  Parses a leaf token, and merges into the branch
  
  @params {Object} tree
  @params {string} branchToken
  @params {string} leftToken;
  @return {Object}