Index: node_modules/d3-transition/src/transition/attrTween.js
===================================================================
--- node_modules/d3-transition/src/transition/attrTween.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
+++ node_modules/d3-transition/src/transition/attrTween.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
@@ -0,0 +1,44 @@
+import {namespace} from "d3-selection";
+
+function attrInterpolate(name, i) {
+  return function(t) {
+    this.setAttribute(name, i.call(this, t));
+  };
+}
+
+function attrInterpolateNS(fullname, i) {
+  return function(t) {
+    this.setAttributeNS(fullname.space, fullname.local, i.call(this, t));
+  };
+}
+
+function attrTweenNS(fullname, value) {
+  var t0, i0;
+  function tween() {
+    var i = value.apply(this, arguments);
+    if (i !== i0) t0 = (i0 = i) && attrInterpolateNS(fullname, i);
+    return t0;
+  }
+  tween._value = value;
+  return tween;
+}
+
+function attrTween(name, value) {
+  var t0, i0;
+  function tween() {
+    var i = value.apply(this, arguments);
+    if (i !== i0) t0 = (i0 = i) && attrInterpolate(name, i);
+    return t0;
+  }
+  tween._value = value;
+  return tween;
+}
+
+export default function(name, value) {
+  var key = "attr." + name;
+  if (arguments.length < 2) return (key = this.tween(key)) && key._value;
+  if (value == null) return this.tween(key, null);
+  if (typeof value !== "function") throw new Error;
+  var fullname = namespace(name);
+  return this.tween(key, (fullname.local ? attrTweenNS : attrTween)(fullname, value));
+}