'Get session based on sessid, or None if not found
Args:
sessid (int or list): Session id(s).
Return:
sessions (Session or list): Session(s) found. This
is a list if input was a list.'

def session_from_sessid(self, sessid):

    if is_iter(sessid):
        return [self.get(sid) for sid in sessid if (sid in self)]
    return self.get(sessid)
