[Haskell-cafe] Motivation for having indexed access in Data.Map?

Hello, I wonder why Data.Map provides the indexed access functions: http://hackage.haskell.org/packages/archive/containers/latest/doc/html/Data-... These functions seem rather out-of-place to me in the map api. The only use case I could think of so far would be to find the median, or in general n-th smallest key, but that does not seem sufficient reason (also, I think there are faster methods for that). Anything else? Regards, Chris