imageSet

imageSet(f,x) is {f(x)} if f(x) is defined, or empty if f(x) is not defined

letting f be function(0 --> 10, 2 --> 20)
find s1 : set of int (9..11) such that s1 = imageSet(f, 0) ${"s1": [10]}

It is finding the solution of f(0) and convert the type to Set.

See it demonstrated here.