human
Solve the following python programming problem given the following code:
def __init__(self, native_image = None, style = 'normal', menu = None) : 
    super (Image, self).__init__ () 
    lbl = QtGui.QLabel () 
    self.widget = lbl 
    if (on_context_menu is not None) : 
        self._set_image (native_image) 
lbl.mousePressEvent = self._cb_redirect 
    if (style == 'clickable') : 
        lbl.setSizePolicy (QtGui.QSizePolicy.Minimum, QtGui.QSizePolicy.Minimum) 
if (menu is not None) : 
        lbl.setContextMenuPolicy (QtCore.Qt.CustomContextMenu) 
        menu_w = menu.get_widget () 
        def on_context_menu(point) : 
            menu_w.exec_ (lbl.mapToGlobal (point)) 
lbl.customContextMenuRequested.connect (on_context_menu) 
self.enable_callback ('activated') 

    
    

    Fix the buggy line: if (on_context_menu is not None) :
assistant
#Here is Python code to fix the buggy line: if (on_context_menu is not None) :
.

if (native_image is not None) :