Due to changes in 1.8 with making vector implement IMapEntry for 2-element vectors, checking whether something is a map entry has become a bit trickier. This enhancement proposes a new function `map-entry?` to encapsulate that check and any future updates to it.
The check for map-entry? will return true if the instance implements java.util.Map$Entry and if it is also a vector, if it's size is exactly 2.
Screened by Joe Smith.