environment/lib/python2.7/site-packages/IPython/utils/notification.py
def _init_observers(self):
        """Initialize observer storage"""

        self.registered_types = set() #set of types that are observed
        self.registered_senders = set() #set of senders that are observed
        self.observers = {}
def _init_observers(self):
        """Initialize observer storage"""

        self.registered_types = set() #set of types that are observed
        self.registered_senders = set() #set of senders that are observed
        self.observers = {}
Initialize observer storage