Index: node_modules/d3-geo/src/length.js
===================================================================
--- node_modules/d3-geo/src/length.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
+++ node_modules/d3-geo/src/length.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
@@ -0,0 +1,53 @@
+import {Adder} from "d3-array";
+import {abs, atan2, cos, radians, sin, sqrt} from "./math.js";
+import noop from "./noop.js";
+import stream from "./stream.js";
+
+var lengthSum,
+    lambda0,
+    sinPhi0,
+    cosPhi0;
+
+var lengthStream = {
+  sphere: noop,
+  point: noop,
+  lineStart: lengthLineStart,
+  lineEnd: noop,
+  polygonStart: noop,
+  polygonEnd: noop
+};
+
+function lengthLineStart() {
+  lengthStream.point = lengthPointFirst;
+  lengthStream.lineEnd = lengthLineEnd;
+}
+
+function lengthLineEnd() {
+  lengthStream.point = lengthStream.lineEnd = noop;
+}
+
+function lengthPointFirst(lambda, phi) {
+  lambda *= radians, phi *= radians;
+  lambda0 = lambda, sinPhi0 = sin(phi), cosPhi0 = cos(phi);
+  lengthStream.point = lengthPoint;
+}
+
+function lengthPoint(lambda, phi) {
+  lambda *= radians, phi *= radians;
+  var sinPhi = sin(phi),
+      cosPhi = cos(phi),
+      delta = abs(lambda - lambda0),
+      cosDelta = cos(delta),
+      sinDelta = sin(delta),
+      x = cosPhi * sinDelta,
+      y = cosPhi0 * sinPhi - sinPhi0 * cosPhi * cosDelta,
+      z = sinPhi0 * sinPhi + cosPhi0 * cosPhi * cosDelta;
+  lengthSum.add(atan2(sqrt(x * x + y * y), z));
+  lambda0 = lambda, sinPhi0 = sinPhi, cosPhi0 = cosPhi;
+}
+
+export default function(object) {
+  lengthSum = new Adder();
+  stream(object, lengthStream);
+  return +lengthSum;
+}