code: function _multiCallback(serverError, serverResponse, callback, interleave, requestedIds){
    var clientResponse = {};
    
    // Handle response errors
    _.each(serverResponse, function(data, id){
      var thisError = serverError;
      if(serverError && data.status.code !== 200){
        thisError = new Error(data.status.msgs.join('. '));
        thisError.code = data.status.code;
      }
      clientResponse[id] = {
        error:  thisError,
        data: data.data
      };
    });
    
    // Handle request level errors
    if(serverError && !serverResponse){
      _.each(requestedIds, function(id){
        if(_.isUndefined(clientResponse[id])){
          clientResponse[id] = {
            error: serverError,
            data: null
          };
        } 
      });
    }
    
    // Interleave validation errors
    if(interleave){
      _.extend(clientResponse, interleave);
    }
    
    callback(clientResponse);
  }
docs: Callback used by Multi methods that
  generates the proper response format