Index: node_modules/d3-force/src/link.js
===================================================================
--- node_modules/d3-force/src/link.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
+++ node_modules/d3-force/src/link.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
@@ -0,0 +1,117 @@
+import constant from "./constant.js";
+import jiggle from "./jiggle.js";
+
+function index(d) {
+  return d.index;
+}
+
+function find(nodeById, nodeId) {
+  var node = nodeById.get(nodeId);
+  if (!node) throw new Error("node not found: " + nodeId);
+  return node;
+}
+
+export default function(links) {
+  var id = index,
+      strength = defaultStrength,
+      strengths,
+      distance = constant(30),
+      distances,
+      nodes,
+      count,
+      bias,
+      random,
+      iterations = 1;
+
+  if (links == null) links = [];
+
+  function defaultStrength(link) {
+    return 1 / Math.min(count[link.source.index], count[link.target.index]);
+  }
+
+  function force(alpha) {
+    for (var k = 0, n = links.length; k < iterations; ++k) {
+      for (var i = 0, link, source, target, x, y, l, b; i < n; ++i) {
+        link = links[i], source = link.source, target = link.target;
+        x = target.x + target.vx - source.x - source.vx || jiggle(random);
+        y = target.y + target.vy - source.y - source.vy || jiggle(random);
+        l = Math.sqrt(x * x + y * y);
+        l = (l - distances[i]) / l * alpha * strengths[i];
+        x *= l, y *= l;
+        target.vx -= x * (b = bias[i]);
+        target.vy -= y * b;
+        source.vx += x * (b = 1 - b);
+        source.vy += y * b;
+      }
+    }
+  }
+
+  function initialize() {
+    if (!nodes) return;
+
+    var i,
+        n = nodes.length,
+        m = links.length,
+        nodeById = new Map(nodes.map((d, i) => [id(d, i, nodes), d])),
+        link;
+
+    for (i = 0, count = new Array(n); i < m; ++i) {
+      link = links[i], link.index = i;
+      if (typeof link.source !== "object") link.source = find(nodeById, link.source);
+      if (typeof link.target !== "object") link.target = find(nodeById, link.target);
+      count[link.source.index] = (count[link.source.index] || 0) + 1;
+      count[link.target.index] = (count[link.target.index] || 0) + 1;
+    }
+
+    for (i = 0, bias = new Array(m); i < m; ++i) {
+      link = links[i], bias[i] = count[link.source.index] / (count[link.source.index] + count[link.target.index]);
+    }
+
+    strengths = new Array(m), initializeStrength();
+    distances = new Array(m), initializeDistance();
+  }
+
+  function initializeStrength() {
+    if (!nodes) return;
+
+    for (var i = 0, n = links.length; i < n; ++i) {
+      strengths[i] = +strength(links[i], i, links);
+    }
+  }
+
+  function initializeDistance() {
+    if (!nodes) return;
+
+    for (var i = 0, n = links.length; i < n; ++i) {
+      distances[i] = +distance(links[i], i, links);
+    }
+  }
+
+  force.initialize = function(_nodes, _random) {
+    nodes = _nodes;
+    random = _random;
+    initialize();
+  };
+
+  force.links = function(_) {
+    return arguments.length ? (links = _, initialize(), force) : links;
+  };
+
+  force.id = function(_) {
+    return arguments.length ? (id = _, force) : id;
+  };
+
+  force.iterations = function(_) {
+    return arguments.length ? (iterations = +_, force) : iterations;
+  };
+
+  force.strength = function(_) {
+    return arguments.length ? (strength = typeof _ === "function" ? _ : constant(+_), initializeStrength(), force) : strength;
+  };
+
+  force.distance = function(_) {
+    return arguments.length ? (distance = typeof _ === "function" ? _ : constant(+_), initializeDistance(), force) : distance;
+  };
+
+  return force;
+}