container/heap: avoid and/or ambiguity in documentation
(per suggestion by Doug McIlroy)
LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/50580046
diff --git a/src/pkg/container/heap/heap.go b/src/pkg/container/heap/heap.go
index 52c8507..3fe2327 100644
--- a/src/pkg/container/heap/heap.go
+++ b/src/pkg/container/heap/heap.go
@@ -22,7 +22,7 @@
// min-heap with the following invariants (established after
// Init has been called or if the data is empty or sorted):
//
-// !h.Less(j, i) for 0 <= i < h.Len() and j = 2*i+1 or 2*i+2 and j < h.Len()
+// !h.Less(j, i) for 0 <= i < h.Len() and 2*i+1 <= j <= 2*i+2 and j < h.Len()
//
// Note that Push and Pop in this interface are for package heap's
// implementation to call. To add and remove things from the heap,
