expvar: document that the Var interface's String method should return a valid JSON...

Change-Id: If4e740f3dbef4053355542eebdd899b3099d872c
Reviewed-on: https://go-review.googlesource.com/21525
Reviewed-by: Andrew Gerrand <adg@golang.org>

diff --git a/src/expvar/expvar.go b/src/expvar/expvar.go
index d675a0230cdbf272370cb36dc23287d212eb8a53..1ec85006b4de92cf82096098fb236e68d0595988 100644 (file)
--- a/src/expvar/expvar.go
+++ b/src/expvar/expvar.go
@@ -38,6 +38,7 @@ import (
 
 // Var is an abstract type for all exported variables.
 type Var interface {
+       // String returns a valid JSON value for the variable.
        String() string
 }