Found by github user asukakenji.
Change-Id: I4c76316b69e8a243fb6bf280283f3722e728d853
Reviewed-on: https://go-review.googlesource.com/17641
Reviewed-by: Robert Griesemer <gri@golang.org>
// Rat returns the rational number corresponding to x;
// or nil if x is an infinity.
-// The result is Exact is x is not an Inf.
+// The result is Exact if x is not an Inf.
// If a non-nil *Rat argument z is provided, Rat stores
// the result in z instead of allocating a new Rat.
func (x *Float) Rat(z *Rat) (*Rat, Accuracy) {