code: function(aa, bb) {
  
                  var mm=info[aa];
  
                  if (loaded[bb] || !mm) {
                      return false;
                  }
  
                  var ii, 
                      rr = mm.expanded, 
                      after = mm.after, 
                      other = info[bb],
                      optional = mm.optional;
  
  
                  // check if this module requires the other directly
                  if (rr && YUI.ArrayUtil.indexOf(rr, bb) > -1) {
                      return true;
                  }
  
                  // check if this module should be sorted after the other
                  if (after && YUI.ArrayUtil.indexOf(after, bb) > -1) {
                      return true;
                  }
  
                  // if loadOptional is not specified, optional dependencies still
                  // must be sorted correctly when present.
                  if (checkOptional && optional && YUI.ArrayUtil.indexOf(optional, bb) > -1) {
                      return true;
                  }
  
                  // check if this module requires one the other supersedes
                  var ss=info[bb] && info[bb].supersedes;
                  if (ss) {
                      for (ii=0; ii<ss.length; ii=ii+1) {
                          if (requires(aa, ss[ii])) {
                              return true;
                          }
                      }
                  }
  
                  // var ss=me.getProvides(bb, true);
                  // if (ss) {
                  //     for (ii in ss) {
                  //         if (requires(aa, ii)) {
                  //             return true;
                  //         }
                  //     }
                  // }
  
                  // external css files should be sorted below yui css
                  if (mm.ext && mm.type == 'css' && !other.ext && other.type == 'css') {
                      return true;
                  }
  
                  return false;
              }
docs: returns true if b is not loaded, and is required directly or by means of modules it supersedes.