Something

import maya.cmds as mc
item='selection'

def User_Select():
    print"USER"
    ctx=mc.scriptCtx( title='Select Something', totalSelectionSets=1,\
     fcs="select -r $Selection1; python(\"Sel_Func('\"+$Selection1[0]+\"')\");",\
     cumulativeLists=False, expandSelectionList=True, setNoSelectionPrompt='Select Object',\
     setSelectionPrompt='Never used', setDoneSelectionPrompt='Never used because setAutoComplete is set',\
     setAutoToggleSelection=True, setSelectionCount=1, setAutoComplete=True)

    mc.setToolTo(ctx)

def Sel_Func(item):
    print"PRINT My FUnction", item
    
    return item