How to use the now.getClient function in now

var users = filegroup.getUsers(function (users) {
      var foundUser = false;
      for (var i = 0; i < users.length; i++){ 
        if(users[i] != callerID){
          // this looks like a valid user to get the file from. :)
          console.log("Trying to get file from: " + users[i]);
          nowjs.getClient(users[i], function(){
            if(this.now === undefined){
              console.log("Undefined clientId for requestFullFileFromUserID (using local) >> " + users[i]);
              localFileFetch(userObj, fname, fileRequesterCallback);
            }else{
              this.now.c_userRequestedFullFile(fname, callerID, fileRequesterCallback);
            }
          });
          foundUser = true;
          break;
        }
      }
      if(!foundUser){
        console.log("Flagged as changed, but no user with file: "+userObj.teamID+" >> "+fname+" >> FETCHING last saved.");
        localFileFetch(userObj, fname, fileRequesterCallback);
      }
    });

this.addUser = function(user) {
        channelUsers.addUser(user);
        if(!adminUser) {
            adminUser = user;
            user.setAdmin(true);
        }
        // Welcome the new member with the last few messages
        nowjs.getClient(user.clientId, function() {
            this.now.handleMessages(messages, true);
            this.now.handleChannelMembers(channelUsers.clientId_user);
        });
        // and notify everyone in the channel of the new members list
        that.getGroup().now.handleMemberJoin(user, channelUsers.clientId_user); //TODO
        // Add this user to the underlying nodejs group...
        that.getGroup().addUser(user.clientId);
    };
    this.removeUser = function(user) {

// be set without already having checked the validity of the room
    var id = that.user.clientId;

    var group = nowjs.getGroup(session.room);
    group.addUser(id);

    // If this is the presenter, set presenter on the group object
    if (session.type == "presenter") {
      group.presenter = id;
    }

    logger.debugPair(id + " entered", that.now.room);
    logger.debugPair("[nowjs.on] connect now object", util.inspect(that.now));

    // Connect Initialization Function to run.
    nowjs.getClient(that.user.clientId, function(){
      if(that.now.hasOwnProperty('initialize') ) that.now.initialize();
    })
  });
});

filegroup.hasClient(id, function (bool) {
    if (bool) {
      //console.log("requesting full file. valid filegroup. :)");
      nowjs.getClient(id, function(){
        if(this.now === undefined){
          console.log("Undefined clientId for requestFullFileFromUserID >> " + id);
        }else{
          this.now.c_userRequestedFullFile(fname, callerID, fileRequesterCallback);
        }
      });
    }
  });
};

var callUserFunction = function(email, func, args) {
  var func = func || '';
  var user = getUser(email || '');
  if(!user) {
    return {'error' : 'User not online'};
  }
  
  if(user && everyone.now[func]) {
    for(var index in user.clients) {
      var clientId = user.clients[index];
      //console.log('execute ' + func + ' with args "' + args[0] + '" for user ' + email + ' with id ' + clientId);
      //Call the function for a specific user
      now.getClient(clientId, function() {
        this.now[func].apply(this, args);
      });
    };
    return {'success' :  true};
  } else {
    return {'error' : 'User function is unknown.'};
  }
};