def getall(self, key):
        """A list of all the values stored under this key.
        
        Returns an empty list if there are no values under this key.
        
        >>> m = MultiMap([('a', 1), ('b', 2), ('b', 3), ('c', 4), ('d', 5), ('c', 6)])
        >>> m.getall('a')
        [1]
        >>> m.getall('b')
        [2, 3]
        >>> m.getall('x')
        []
        
        """
        key = self._conform_key(key)
        return [self._pairs[i][1] for i in self._key_ids[key]]