My own "Hello, World!" Maya plug-in

Yestarday, I used Maya devkit example to learn Maya plug-ins. Today, I will create my own alternative Hello World plug-in!
import maya.OpenMaya as om
import maya.OpenMayaMPx as ommpx

class AR_HelloWorldCmd(ommpx.MPxCommand):
    """
    A command that prints a string to the console.
    """
    
    ## the name of the command
    kPluginCmdName = 'ar_helloWorld'
   
    def __init__(self):
        """
        Initialize the instance.
        """
        ommpx.MPxCommand.__init__(self)
   
    def doIt(self, args):
        """
        Print string to the console.
        """
        print('Hello, world!')
   
    @classmethod
    def cmdCreator(cls):
        """
        Return pointer to proxy object.It has to always call this method when creating MPx objects in scripted plug-ins.
        """
        return ommpx.asMPxPtr(cls())

def initializePlugin(obj):
    """
    Initialize the plug-in.
    """
    plugin = ommpx.MFnPlugin(
        obj,
        'Meng',
        '1.0',
        'Any'
    )
    try:
        plugin.registerCommand(
            AR_HelloWorldCmd.kPluginCmdName,
            AR_HelloWorldCmd.cmdCreator
        )
    except:
        raise Exception(
            'Failed to register command: %s'%
            AR_HelloWorldCmd.kPluginCmdName
        )

def uninitializePlugin(obj):
    """
    Uninitialize the plug-in.
    """
    plugin = ommpx.MFnPlugin(obj)
    try:
        plugin.deregisterCommand(AR_HelloWorldCmd.kPluginCmdName)      
    except:
        raise Exception(
            'Failed to unregister command: %s'%
            AR_HelloWorldCmd.kPluginCmdName
        )

It is critical to note again that you must unload and then reload a plug-in to see changes that you are making in an external text editor become active in Maya.