(self, key)
Return True if the keyed message exists, False otherwise.
Return True if the keyed message exists, False otherwise.
Return True if the keyed message exists False otherwise .
def __contains__(self, key):
        """Return True if the keyed message exists, False otherwise."""
        raise NotImplementedError('Method must be implemented by subclass')
def __contains__ ( self , key ) : raise NotImplementedError ( 'Method must be implemented by subclass' )