Index: node_modules/d3-shape/src/curve/step.js
===================================================================
--- node_modules/d3-shape/src/curve/step.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
+++ node_modules/d3-shape/src/curve/step.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
@@ -0,0 +1,53 @@
+function Step(context, t) {
+  this._context = context;
+  this._t = t;
+}
+
+Step.prototype = {
+  areaStart: function() {
+    this._line = 0;
+  },
+  areaEnd: function() {
+    this._line = NaN;
+  },
+  lineStart: function() {
+    this._x = this._y = NaN;
+    this._point = 0;
+  },
+  lineEnd: function() {
+    if (0 < this._t && this._t < 1 && this._point === 2) this._context.lineTo(this._x, this._y);
+    if (this._line || (this._line !== 0 && this._point === 1)) this._context.closePath();
+    if (this._line >= 0) this._t = 1 - this._t, this._line = 1 - this._line;
+  },
+  point: function(x, y) {
+    x = +x, y = +y;
+    switch (this._point) {
+      case 0: this._point = 1; this._line ? this._context.lineTo(x, y) : this._context.moveTo(x, y); break;
+      case 1: this._point = 2; // falls through
+      default: {
+        if (this._t <= 0) {
+          this._context.lineTo(this._x, y);
+          this._context.lineTo(x, y);
+        } else {
+          var x1 = this._x * (1 - this._t) + x * this._t;
+          this._context.lineTo(x1, this._y);
+          this._context.lineTo(x1, y);
+        }
+        break;
+      }
+    }
+    this._x = x, this._y = y;
+  }
+};
+
+export default function(context) {
+  return new Step(context, 0.5);
+}
+
+export function stepBefore(context) {
+  return new Step(context, 0);
+}
+
+export function stepAfter(context) {
+  return new Step(context, 1);
+}