Make setAnnotations' boolean parameter optional. (#851)

diff --git a/dygraph-externs.js b/dygraph-externs.js
index 02330f8..e8e2c42 100644 (file)
--- a/dygraph-externs.js
+++ b/dygraph-externs.js
@@ -142,7 +142,7 @@ Dygraph.prototype.visibility;
 /** @type {function(number, boolean)} */
 Dygraph.prototype.setVisibility;
 
-/** @type {function(Array.<Object>, boolean)} */
+/** @type {function(Array.<Object>, boolean=)} */
 Dygraph.prototype.setAnnotations;
 
 /** @type {function(): Array.<Object>} */