Return the number of value_type objects within this unordered multiset that are equivalent to the specified key. The behavior is undefined unless key is equivalent to the elements of at most one equivalent-key group in this unordered multiset.
Declared in <bslstl_unorderedmultiset.h>
template<class LOOKUP_KEY>
size_type
count(LOOKUP_KEY const& key) const
requires BloombergLP::bslmf::IsTransparentPredicate<HASH, LOOKUP_KEY>::value
&& BloombergLP::bslmf::IsTransparentPredicate<EQUAL,LOOKUP_KEY>::value;