Maya python UI passing argument in command

Here is example of Maya UI code in case you need to build in a command to UI element which passes an argument.
More about this technique here:
http://download.autodesk.com/us/maya/2011help/pymel/ui.html

Note - this is all one function myUI(), where buttonPressed is function defined inside that function. It doesn`t have to be, but this way it is localised and only visible to the UI function.

import maya.cmds as mc

def myUI():

    def buttonPressed(name):
        print "pressed %s!" % name

    win = mc.window(title="My Window")
    layout = mc.columnLayout()
    btn = mc.button( command = lambda *args: buttonPressed('chad') )

    showWindow()