function joinClasses(className/*, ... */) {
  if (!className) {
    className = '';
  }
  var nextClass;
  var argLength = arguments.length;
  if (argLength > 1) {
    for (var ii = 1; ii < argLength; ii++) {
      nextClass = arguments[ii];
      if (nextClass) {
        className = (className ? className + ' ' : '') + nextClass;
      }
    }
  }
  return className;
}
Allows extraction of a minified key. Let's the build system minify keys
without loosing the ability to dynamically use key strings as values
themselves. Pass in an object with a single key/val pair and it will return
you the string key of that single record. Suppose you want to grab the
value for a key 'className' inside of an object. Key/val minification may
have aliased that key to be 'xa12'. keyOf({className: null}) will return
'xa12' in that case. Resolve keys you want to use once at startup time, then
reuse those resolutions.