# map:keys - XPath XQuery Reference

Returns a sequence containing all the keys present in a mapnondeterministic-wrt-orderingcontext-independentfocus-independentThe function map:keys takes any map
            as its $map argument and returns the keys that are present in the map as
            a sequence of atomic values, in implementation-dependent order.The function is non-deterministic with respect to ordering
            (see ). This means that two calls with the same argument
            are not guaranteed to produce the results in the same order.map:keys(map{1:"yes", 2:"no"})(1,2)The result is in implementation-dependent order.The number of items in the result will be the same as the number of
            entries in the map, and the result sequence will contain no duplicate values.