Does the key exist?
        This method will check to see if it has expired too.

def has_key(self, key):
        """Does the key exist?
        This method will check to see if it has expired too.
        """
        if key in self._dict:
            try: 
                self[key]
                return True
            except ValueError:
                return False
            except KeyError:
                return False
        return False