Check if timeline exists and when somebody tries to edit non existing timelime display error message. Add TODO regarding error message customization for Timeline. Add support for calendar widget in timeline for both gsoc and ghop programs (gsoc was hardcoded before). Patch by: Pawel Solyga Review by: to-be-reviewed

"""Multi-consumer multi-producer dispatching mechanism

Originally based on pydispatch (BSD) http://pypi.python.org/pypi/PyDispatcher/2.0.1
See license.txt for original license.

Heavily modified for Django's purposes.
"""

from django.dispatch.dispatcher import Signal