Index: node_modules/d3-array/src/superset.js
===================================================================
--- node_modules/d3-array/src/superset.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
+++ node_modules/d3-array/src/superset.js	(revision e4c61dd6cd86e06265bc2bd91adba84a0f04044a)
@@ -0,0 +1,19 @@
+export default function superset(values, other) {
+  const iterator = values[Symbol.iterator](), set = new Set();
+  for (const o of other) {
+    const io = intern(o);
+    if (set.has(io)) continue;
+    let value, done;
+    while (({value, done} = iterator.next())) {
+      if (done) return false;
+      const ivalue = intern(value);
+      set.add(ivalue);
+      if (Object.is(io, ivalue)) break;
+    }
+  }
+  return true;
+}
+
+function intern(value) {
+  return value !== null && typeof value === "object" ? value.valueOf() : value;
+}