flow like the river

VISUALIZACION/node_modules/graphql/jsutils/instanceOf.js.flow

@@ -0,0 +1,52 @@
+// @flow strict
+import inspect from './inspect';
+
+/**
+ * A replacement for instanceof which includes an error warning when multi-realm
+ * constructors are detected.
+ */
+declare function instanceOf(
+  value: mixed,
+  constructor: mixed,
+): boolean %checks(value instanceof constructor);
+
+// See: https://expressjs.com/en/advanced/best-practice-performance.html#set-node_env-to-production
+// See: https://webpack.js.org/guides/production/
+export default process.env.NODE_ENV === 'production'
+  ? // istanbul ignore next (See: 'https://github.com/graphql/graphql-js/issues/2317')
+    // eslint-disable-next-line no-shadow
+    function instanceOf(value: mixed, constructor: mixed): boolean {
+      return value instanceof constructor;
+    }
+  : // eslint-disable-next-line no-shadow
+    function instanceOf(value: any, constructor: any): boolean {
+      if (value instanceof constructor) {
+        return true;
+      }
+      if (typeof value === 'object' && value !== null) {
+        const className = constructor.prototype[Symbol.toStringTag];
+        const valueClassName =
+          // We still need to support constructor's name to detect conflicts with older versions of this library.
+          Symbol.toStringTag in value
+            ? value[Symbol.toStringTag]
+            : value.constructor?.name;
+        if (className === valueClassName) {
+          const stringifiedValue = inspect(value);
+          throw new Error(
+            `Cannot use ${className} "${stringifiedValue}" from another module or realm.
+
+Ensure that there is only one instance of "graphql" in the node_modules
+directory. If different versions of "graphql" are the dependencies of other
+relied on modules, use "resolutions" to ensure only one version is installed.
+
+https://yarnpkg.com/en/docs/selective-version-resolutions
+
+Duplicate "graphql" modules cannot be used at the same time since different
+versions may have different capabilities and behavior. The data from one
+version used in the function from another could produce confusing and
+spurious results.`,
+          );
+        }
+      }
+      return false;
+    };