def error_msg_wx(msg, parent=None):
 dialog = wx.MessageDialog(parent=parent, message=msg, caption='Matplotlib backend_wx error', style=(wx.OK | wx.CENTRE))
 dialog.ShowModal()
 dialog.Destroy()
 return None

def error_msg_wx ( msg , parent = None ) : dialog = wx . MessageDialog ( parent = parent , message = msg , caption = 'Matplotlib backend_wx error' , style = ( wx . OK | wx . CENTRE ) ) dialog . ShowModal ( ) dialog . Destroy ( ) return None
signal an error condition -- in a gui .