Return a reference providing modifiable access to the mapped value associated with a key that is equivalent to the specified key in this map, if such an entry exists; otherwise throw a std::out_of_range exception. Note that this method is not exception-neutral.
Declared in <bdlc_flathashmap.h>
template<class LOOKUP_KEY>
VALUE&
at(LOOKUP_KEY const& key)
requires BloombergLP::bslmf::IsTransparentPredicate<HASH, LOOKUP_KEY>::value
&& BloombergLP::bslmf::IsTransparentPredicate<EQUAL,LOOKUP_KEY>::value;