def apply_extra_context(extra_context, context):
    """
    Adds items from extra_context dict to context.  If a value in extra_context
    is callable, then it is called and the result is added to context.
    """
    for key, value in extra_context.iteritems():
        if callable(value):
            context[key] = value()
        else:
            context[key] = value
