MayaHelloWorld.py

import maya.api.OpenMaya as om
 
def maya_useNewAPI():
    pass

class HelloWorld(om.MPxCommand):
    kPluginCmdName = "HelloWorld"

    def __init__(self):
        om.MPxCommand.__init__(self)

    @staticmethod
    def cmdCreator():
        return HelloWorld()

    def doIt(self, args):
        print "Hello World."
 
def initializePlugin(mobject):
    plugin = om.MFnPlugin(mobject)
    plugin.registerCommand(
        HelloWorld.kPluginCmdName, HelloWorld.cmdCreator
    )

def uninitializePlugin(mobject):
    pluginFn = om.MFnPlugin(mobject)
    pluginFn.deregisterCommand(HelloWorld.kPluginCmdName)