C++ STL: Why is there no upper_bound equivalent that retrieves the greatest element smaller then a specific key?

C++ STL: Why is there no upper_bound equivalent that retrieves the
greatest element smaller then a specific key?

References

Reference NO 1

http://stackoverflow.com/questions/15189194/c-stl-why-is-there-no-upper-bound-equivalent-that-retrieves-the-greatest-elem

Reference NO 2

http://stackoverflow.com/questions/11381487/c-stl-algorithms-upper-bound-that-is-not-strictly-greater

Reference NO 3

http://stackoverflow.com/questions/3761914/storing-and-retrieving-multiple-keys-in-c

Reference NO 4

http://www.cplusplus.com/reference/set/multiset/

Reference NO 5

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.55.2789&rep=rep1&type=ps

Reference NO 6

http://cs.fit.edu/~mmahoney/cse2050/how2cpp.html

Reference NO 7

http://csis.pace.edu/~bergin/STL/Chapter2STL.html

Reference NO 8

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