mekso unary operator: the set of all fixed points of function a

The output is an (unordered) set of all of the fixed/stationary/self-mapping points of the input function a; in other words, it the set of all x that are in the domain of a such that a(x) = x. Beware that a may have a larger range than intended (for example, e^x makes sense even for some matrix-valued x). Use mau'au for quoting a.