Index: node_modules/d3-hierarchy/src/cluster.js
===================================================================
--- node_modules/d3-hierarchy/src/cluster.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
+++ node_modules/d3-hierarchy/src/cluster.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
@@ -0,0 +1,84 @@
+function defaultSeparation(a, b) {
+  return a.parent === b.parent ? 1 : 2;
+}
+
+function meanX(children) {
+  return children.reduce(meanXReduce, 0) / children.length;
+}
+
+function meanXReduce(x, c) {
+  return x + c.x;
+}
+
+function maxY(children) {
+  return 1 + children.reduce(maxYReduce, 0);
+}
+
+function maxYReduce(y, c) {
+  return Math.max(y, c.y);
+}
+
+function leafLeft(node) {
+  var children;
+  while (children = node.children) node = children[0];
+  return node;
+}
+
+function leafRight(node) {
+  var children;
+  while (children = node.children) node = children[children.length - 1];
+  return node;
+}
+
+export default function() {
+  var separation = defaultSeparation,
+      dx = 1,
+      dy = 1,
+      nodeSize = false;
+
+  function cluster(root) {
+    var previousNode,
+        x = 0;
+
+    // First walk, computing the initial x & y values.
+    root.eachAfter(function(node) {
+      var children = node.children;
+      if (children) {
+        node.x = meanX(children);
+        node.y = maxY(children);
+      } else {
+        node.x = previousNode ? x += separation(node, previousNode) : 0;
+        node.y = 0;
+        previousNode = node;
+      }
+    });
+
+    var left = leafLeft(root),
+        right = leafRight(root),
+        x0 = left.x - separation(left, right) / 2,
+        x1 = right.x + separation(right, left) / 2;
+
+    // Second walk, normalizing x & y to the desired size.
+    return root.eachAfter(nodeSize ? function(node) {
+      node.x = (node.x - root.x) * dx;
+      node.y = (root.y - node.y) * dy;
+    } : function(node) {
+      node.x = (node.x - x0) / (x1 - x0) * dx;
+      node.y = (1 - (root.y ? node.y / root.y : 1)) * dy;
+    });
+  }
+
+  cluster.separation = function(x) {
+    return arguments.length ? (separation = x, cluster) : separation;
+  };
+
+  cluster.size = function(x) {
+    return arguments.length ? (nodeSize = false, dx = +x[0], dy = +x[1], cluster) : (nodeSize ? null : [dx, dy]);
+  };
+
+  cluster.nodeSize = function(x) {
+    return arguments.length ? (nodeSize = true, dx = +x[0], dy = +x[1], cluster) : (nodeSize ? [dx, dy] : null);
+  };
+
+  return cluster;
+}