Index: node_modules/d3-shape/src/stack.js
===================================================================
--- node_modules/d3-shape/src/stack.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
+++ node_modules/d3-shape/src/stack.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
@@ -0,0 +1,58 @@
+import array from "./array.js";
+import constant from "./constant.js";
+import offsetNone from "./offset/none.js";
+import orderNone from "./order/none.js";
+
+function stackValue(d, key) {
+  return d[key];
+}
+
+function stackSeries(key) {
+  const series = [];
+  series.key = key;
+  return series;
+}
+
+export default function() {
+  var keys = constant([]),
+      order = orderNone,
+      offset = offsetNone,
+      value = stackValue;
+
+  function stack(data) {
+    var sz = Array.from(keys.apply(this, arguments), stackSeries),
+        i, n = sz.length, j = -1,
+        oz;
+
+    for (const d of data) {
+      for (i = 0, ++j; i < n; ++i) {
+        (sz[i][j] = [0, +value(d, sz[i].key, j, data)]).data = d;
+      }
+    }
+
+    for (i = 0, oz = array(order(sz)); i < n; ++i) {
+      sz[oz[i]].index = i;
+    }
+
+    offset(sz, oz);
+    return sz;
+  }
+
+  stack.keys = function(_) {
+    return arguments.length ? (keys = typeof _ === "function" ? _ : constant(Array.from(_)), stack) : keys;
+  };
+
+  stack.value = function(_) {
+    return arguments.length ? (value = typeof _ === "function" ? _ : constant(+_), stack) : value;
+  };
+
+  stack.order = function(_) {
+    return arguments.length ? (order = _ == null ? orderNone : typeof _ === "function" ? _ : constant(Array.from(_)), stack) : order;
+  };
+
+  stack.offset = function(_) {
+    return arguments.length ? (offset = _ == null ? offsetNone : _, stack) : offset;
+  };
+
+  return stack;
+}