code: function aliasByFunction (obj, convert) {
    // have to create another object so that ie8 won't infinite loop on keys
    var output = {};
    for (var key in obj) output[convert(key)] = obj[key];
    return output;
  }
docs: Convert the keys in an `obj` using a `convert` function.
  
  @param {Object} obj
  @param {Function} convert