    "Given a function with return type `Y`, and a second
     function with a single parameter also of type `Y`,
     return the composition of the two functions. The
     first function may have any number of parameters.

     For any such functions `f()` and `g()`,

         compose(g,f)(*args)==g(f(*args))

     for every possible argument tuple `args` of `f()`."
    see(`function curry`, `function uncurry`)
    shared Callable<X,Args> compose<X,Y,Args>(X(Y) x, Callable<Y,Args> y)
            given Args satisfies Anything[]
                   //=> flatten((Args args) => x(y(*args)));
                   => flatten((Args args) => x(unflatten(y)(args)));