Index: node_modules/d3-transition/src/transition/duration.js
===================================================================
--- node_modules/d3-transition/src/transition/duration.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
+++ node_modules/d3-transition/src/transition/duration.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
@@ -0,0 +1,23 @@
+import {get, set} from "./schedule.js";
+
+function durationFunction(id, value) {
+  return function() {
+    set(this, id).duration = +value.apply(this, arguments);
+  };
+}
+
+function durationConstant(id, value) {
+  return value = +value, function() {
+    set(this, id).duration = value;
+  };
+}
+
+export default function(value) {
+  var id = this._id;
+
+  return arguments.length
+      ? this.each((typeof value === "function"
+          ? durationFunction
+          : durationConstant)(id, value))
+      : get(this.node(), id).duration;
+}