gistfile1.py

# event.py
class Event():
  # some implentation of adding, deleting and firing event handlers
  pass

class ErrorEvent(Event):
  pass

# some_file.py
from event import ErrorEvent

def do_something():
  ErrorEvent.fire("Temperature is to high")

# main.py
from event import ErrorEvent
from some_file import do_something

def handle_error(msg):
  print("Handled error: %s" % msg)

ErrorEvent.add_handler(handle_error)
do_something # will print: "Handled error: Temperature to high"