diff --git a/README.md b/README.md
index 5a4b459..f5dc583 100644
--- a/README.md
+++ b/README.md
@@ -130,9 +130,17 @@ there is cached result.
 
 Builtin IO functions are mocked to cache IO. Current list of builtin cached
 functions is:
-- `Date` constructor
+- `Date`
 - `Math.random()`
 - `fetch`
+- `Response` methods:
+    - `arrayBuffer`
+    - `blob`
+    - `formData`
+    - `json`
+    - `text`
+- `setTimeout`
+- `clearTimeout`
 
 If you want to make your own own function IO-caching, or import third party
 function and make it IO-caching, then you should use `IO` pragma.
diff --git a/src/cmd.js b/src/cmd.js
index 8be9c2a..73f9aad 100644
--- a/src/cmd.js
+++ b/src/cmd.js
@@ -768,6 +768,11 @@ const on_deferred_call = (state, call, calltree_changed_token, logs) => {
   }
 }
 
+// TODO test
+const clear_io_cache = state => {
+  return run_code({...state, io_cache: null})
+}
+
 const do_load_dir = (state, dir) => {
   const collect_files = dir => dir.kind == 'file' 
     ? [dir]
@@ -848,5 +853,6 @@ export const COMMANDS = {
   external_imports_loaded,
   eval_modules_finished,
   on_deferred_call,
+  clear_io_cache,
   calltree: calltree_commands,
 }
diff --git a/src/record_io.js b/src/record_io.js
index fbadd9f..2784867 100644
--- a/src/record_io.js
+++ b/src/record_io.js
@@ -20,7 +20,11 @@ const io_patch = (cxt, path, use_context = false) => {
 
   const original = obj[method]
   obj[method] = function(...args) {
-    // TODO guard calls from prev run
+    // TODO if called from previous version of code (calltree_changed_token is
+    // different), then do not call IO function and throw error to finish
+    // previous run ASAP
+
+    // TODO remove
     console.error('patched method', name, {
         io_cache_is_recording: cxt.io_cache_is_recording, 
         io_cache_is_replay_aborted: cxt.io_cache_is_replay_aborted, 
@@ -28,14 +32,18 @@ const io_patch = (cxt, path, use_context = false) => {
           ? cxt.io_cache.length
           : cxt.io_cache_index
     })
-    // TODO guard that in find_call io methods are not called?
-    // if(searched_location != null) {
-    //   throw new Error('illegal state')
-    // }
+
+    // sanity check
+    if(cxt.searched_location != null) {
+      throw new Error('illegal state')
+    }
+
     if(cxt.io_cache_is_replay_aborted) {
       // Try to finish fast
       throw new Error('io replay aborted')
-    } else if(cxt.io_cache_is_recording) {
+    }
+
+    if(cxt.io_cache_is_recording) {
       let ok, value, error
       const has_new_target = new.target != null
       try {
@@ -141,6 +149,11 @@ const io_patch = (cxt, path, use_context = false) => {
           cxt.io_cache_resolver_is_set = true
 
           original_setTimeout(() => {
+            if(cxt.io_cache_is_replay_aborted) {
+              console.error('RESOLVER ABORTED')
+              return
+            }
+
             // TODO guard from previous run
             console.error('resolver', {
               io_cache_is_replay_aborted: cxt.io_cache_is_replay_aborted,
@@ -151,38 +164,32 @@ const io_patch = (cxt, path, use_context = false) => {
 
             // TODO check if call from prev run 
 
-            if(cxt.io_cache_is_replay_aborted) {
-              console.error('RESOLVER ABORTED')
-              return
-            }
-
+            // Sanity check
             if(cxt.io_cache_index >= cxt.io_cache.length) {
-              // TODO Do nothing or what?
-              // Should not gonna happen
               throw new Error('illegal state')
+            }  
+
+            const next_event = cxt.io_cache[cxt.io_cache_index]
+            if(next_event.type == 'call') {
+              // TODO Call not happened, replay?
+              cxt.io_cache_is_replay_aborted = true
             } else {
-              const next_event = cxt.io_cache[cxt.io_cache_index]
-              if(next_event.type == 'call') {
-                // TODO Call not happened, replay?
-                cxt.io_cache_is_replay_aborted = true
-              } else {
-                while(
-                  cxt.io_cache_index < cxt.io_cache.length 
-                  && 
-                  cxt.io_cache[cxt.io_cache_index].type == 'resolution'
-                ) {
-                  const resolution = cxt.io_cache[cxt.io_cache_index]
-                  const resolver = cxt.io_cache_resolvers.get(resolution.index)
+              while(
+                cxt.io_cache_index < cxt.io_cache.length 
+                && 
+                cxt.io_cache[cxt.io_cache_index].type == 'resolution'
+              ) {
+                const resolution = cxt.io_cache[cxt.io_cache_index]
+                const resolver = cxt.io_cache_resolvers.get(resolution.index)
 
-                  cxt.io_cache_index++
+                cxt.io_cache_index++
 
-                  if(cxt.io_cache[resolution.index].name == 'setTimeout') {
-                    resolver()
-                  } else {
-                    resolver(cxt.io_cache[resolution.index].value)
-                  }
-                  console.log('RESOLVE', cxt.io_cache_index, resolution.index)
+                if(cxt.io_cache[resolution.index].name == 'setTimeout') {
+                  resolver()
+                } else {
+                  resolver(cxt.io_cache[resolution.index].value)
                 }
+                console.log('RESOLVE', cxt.io_cache_index, resolution.index)
               }
             }
 
@@ -192,9 +199,6 @@ const io_patch = (cxt, path, use_context = false) => {
         cxt.io_cache_index++
 
         if(call.ok) {
-          // TODO resolve promises in the same order they were resolved on
-          // initial execution
-
           if(call.value instanceof cxt.window.Promise) {
             return new Promise(resolve => {
               cxt.io_cache_resolvers.set(cxt.io_cache_index - 1, resolve)
diff --git a/test/test.js b/test/test.js
index 75fe6cc..4a5735a 100644
--- a/test/test.js
+++ b/test/test.js
@@ -3127,8 +3127,6 @@ const y = x()`
       console.log(await delay(0))
     `
 
-    console.log('CODE2', code2.slice(75))
-
     const next = await command_input_async(i, code2, 0)
 
     // Assert cache was used