def value_count(self, key):
check_not_none(key, "<STR_LIT>")<EOL>return self._encode_invoke(transactional_multi_map_value_count_codec, key=self._to_data(key))<EOL>
Transactional implementation of :func:`MultiMap.value_count(key)
<hazelcast.proxy.multi_map.MultiMap.value_count>`

:param key: (object), the key whose number of values is to be returned.
:return: (int), the number of values matching the given key in the multimap.