wrap runPython in async (#1212)

pyscriptjs/src/utils.ts

@@ -112,3 +112,26 @@ export function createSingularWarning(msg: string, sentinelText: string | null =
         _createAlertBanner(msg, 'warning');
     }
 }
+
+/**
+ * @returns A new asynchronous lock
+ * @private
+ */
+export function createLock() {
+    // This is a promise that is resolved when the lock is open, not resolved when lock is held.
+    let _lock = Promise.resolve();
+
+    /**
+     * Acquire the async lock
+     * @returns A zero argument function that releases the lock.
+     * @private
+     */
+    async function acquireLock() {
+      const old_lock = _lock;
+      let releaseLock: () => void;
+      _lock = new Promise((resolve) => (releaseLock = resolve));
+      await old_lock;
+      return releaseLock;
+    }
+    return acquireLock;
+  }