code: function(into, from) {
    for (var key in from) {
      if (into[key] instanceof Object &&
          !(into[key] instanceof Array) &&
          !(into[key] instanceof Function)) {
        merge_(into[key], from[key]);
      } else {
        into[key] = from[key];
      }
    }
    return into;
  }
docs: Merge config objects together.
  
  @private
  @param {Object} into
  @param {Object} from
  
  @return {Object} The 'into' config.