'Get info about a session.
Parameters
session : int
Session number to retrieve. The current session is 0, and negative
numbers count back from current session, so -1 is the previous session.
Returns
session_id : int
Session ID number
start : datetime
Timestamp for the start of the session.
end : datetime
Timestamp for the end of the session, or None if IPython crashed.
num_cmds : int
Number of commands run, or None if IPython crashed.
remark : unicode
A manually set description.'

def get_session_info(self, session=0):

    if (session <= 0):
        session += self.session_number
    return super(HistoryManager, self).get_session_info(session=session)
