flow like the river

BACK_BACK/node_modules/graphql/jsutils/Path.js.flow

@@ -0,0 +1,30 @@
+// @flow strict
+export type Path = {|
+  +prev: Path | void,
+  +key: string | number,
+  +typename: string | void,
+|};
+
+/**
+ * Given a Path and a key, return a new Path containing the new key.
+ */
+export function addPath(
+  prev: $ReadOnly<Path> | void,
+  key: string | number,
+  typename: string | void,
+): Path {
+  return { prev, key, typename };
+}
+
+/**
+ * Given a Path, return an Array of the path keys.
+ */
+export function pathToArray(path: ?$ReadOnly<Path>): Array<string | number> {
+  const flattened = [];
+  let curr = path;
+  while (curr) {
+    flattened.push(curr.key);
+    curr = curr.prev;
+  }
+  return flattened.reverse();
+}