+-- | Takes a function @f@ and an exponent @n@. Returns a new function,
+-- @g@, defined by g(x) = (f(x))^n. This is /not/ @f@ composed
+-- with itself @n@ times.
+--
+-- ==== __Examples__
+--
+-- >>> let square x = x**2
+-- >>> square 2
+-- 4.0
+-- >>> let f = fexp square 3
+-- >>> f 2
+-- 64.0
+--