[#BloombergLP-bdlc-FlatHashSet-insert-08] = xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdlc.adoc[bdlc]::xref:BloombergLP/bdlc/FlatHashSet.adoc[FlatHashSet]::insert :relfileprefix: ../../../ :mrdocs: Insert the specified `key` into this set if a key equivalent to `k` does not already exist in this set; otherwise, this method has no effect. Return a pair containing an `iterator` referring to the newly inserted element and `true` if a element was inserted. Return a pair containing an `iterator` to an existing element and `false` if the value already existed in the set. The supplied `const_iterator` is ignored. == Synopsis Declared in `<bdlc_flathashset.h>` [source,cpp,subs="verbatim,replacements,macros,-callouts"] ---- template<class LOOKUP_KEY> xref:BloombergLP/bdlc/FlatHashSet/iterator.adoc[iterator] insert( xref:BloombergLP/bdlc/FlatHashSet/const_iterator.adoc[const_iterator], LOOKUP_KEY&& key) requires BloombergLP::bslmf::IsTransparentPredicate<HASH, LOOKUP_KEY>::value && BloombergLP::bslmf::IsTransparentPredicate<EQUAL,LOOKUP_KEY>::value && bsl::is_convertible<LOOKUP_KEY&&, const_iterator>::value == false && bsl::is_convertible<const_iterator, LOOKUP_KEY&&>::value == false; ---- [.small]#Created with https://www.mrdocs.com[MrDocs]#