diff --git a/sentence/iterators101.ipynb b/iterators101.ipynb
similarity index 88%
rename from sentence/iterators101.ipynb
rename to iterators101.ipynb
index 8be4902..766333b 100644
--- a/sentence/iterators101.ipynb
+++ b/iterators101.ipynb
@@ -38,6 +38,21 @@
   {
    "cell_type": "code",
    "execution_count": 3,
+   "id": "18fb40fc-a704-4c2a-9e31-50294e370c7a",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "func YIELD(_ int) bool {\n",
+    "    return true\n",
+    "}\n",
+    "\n",
+    "%%\n",
+    "gen123(YIELD)  // returns no value"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
    "id": "05dbdca4-13d4-4a12-a982-4ca9dfd8fad5",
    "metadata": {},
    "outputs": [],
@@ -57,7 +72,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 4,
+   "execution_count": 5,
    "id": "8c9bb0ec-065a-4cad-8250-2da7c9d71d13",
    "metadata": {},
    "outputs": [
@@ -90,7 +105,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 5,
+   "execution_count": 6,
    "id": "0b8e68c2-0631-4f8e-95d4-dc659eeea9b5",
    "metadata": {},
    "outputs": [
@@ -123,7 +138,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 6,
+   "execution_count": 7,
    "id": "8d408926-a972-4fec-a863-776afa7c946c",
    "metadata": {},
    "outputs": [
@@ -151,15 +166,11 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 49,
+   "execution_count": 8,
    "id": "79994c10-86c9-4fb1-870a-3e6c05cbcbe8",
    "metadata": {},
    "outputs": [],
    "source": [
-    "func notWord(r rune) bool {\n",
-    "\treturn !(unicode.IsLetter(r) || unicode.IsDigit(r) || r == '-')\n",
-    "}\n",
-    "\n",
     "// Sentence wraps a piece of text and yields its words lazily.\n",
     "type Sentence struct {\n",
     "\ttext string\n",
@@ -176,6 +187,10 @@
     "\treturn fmt.Sprintf(\"Sentence{%#v}\", shortRepr(s.text, 30))\n",
     "}\n",
     "\n",
+    "func notWord(r rune) bool {\n",
+    "\treturn !(unicode.IsLetter(r) || unicode.IsDigit(r) || r == '-')\n",
+    "}\n",
+    "\n",
     "// Words returns an iterator over the words in the sentence.\n",
     "func (s *Sentence) Words() iter.Seq[string] {\n",
     "\treturn strings.FieldsFuncSeq(s.text, notWord)\n",
@@ -196,7 +211,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 51,
+   "execution_count": 9,
    "id": "1ae93130-4875-4e81-84d2-9b44b0834adc",
    "metadata": {},
    "outputs": [
@@ -205,7 +220,8 @@
      "output_type": "stream",
      "text": [
       "{The time has come to speak of many things}\n",
-      "main.Sentence\tmain.Sentence{text:\"The time has come to speak of many things\"}The\n",
+      "main.Sentence\tmain.Sentence{text:\"The time has come to speak of many things\"}\n",
+      "The\n",
       "time\n",
       "has\n",
       "come\n",
@@ -222,7 +238,7 @@
     "s := Sentence{\"The time has come to speak of many things\"}\n",
     " \n",
     "fmt.Println(s) // calls Sentence.String() via the Stringer interface\n",
-    "fmt.Printf(\"%T\\t%#v\", s, s)\n",
+    "fmt.Printf(\"%T\\t%#v\\n\", s, s)\n",
     "\n",
     "for word := range s.Words() {\n",
     "    fmt.Println(word)\n",
@@ -231,7 +247,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 48,
+   "execution_count": 10,
    "id": "5db65ffb-c7d0-4346-8785-158b659f6fd4",
    "metadata": {},
    "outputs": [
diff --git a/sentence/sentence.ipynb b/sentence/sentence.ipynb
new file mode 100644
index 0000000..0d66287
--- /dev/null
+++ b/sentence/sentence.ipynb
@@ -0,0 +1,131 @@
+{
+ "cells": [
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "id": "79994c10-86c9-4fb1-870a-3e6c05cbcbe8",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "// Sentence wraps a piece of text and yields its words lazily.\n",
+    "type Sentence struct {\n",
+    "\ttext string\n",
+    "}\n",
+    "\n",
+    "// New returns a Sentence over the given text.\n",
+    "func New(text string) *Sentence {\n",
+    "\treturn &Sentence{text: text}\n",
+    "}\n",
+    "\n",
+    "// String truncates long text so debugging output for\n",
+    "// a huge sentence stays readable.\n",
+    "func (s *Sentence) String() string {\n",
+    "\treturn fmt.Sprintf(\"Sentence{%#v}\", shortRepr(s.text, 30))\n",
+    "}\n",
+    "\n",
+    "func notWord(r rune) bool {\n",
+    "\treturn !(unicode.IsLetter(r) || unicode.IsDigit(r) || r == '-')\n",
+    "}\n",
+    "\n",
+    "// Words returns an iterator over the words in the sentence.\n",
+    "func (s *Sentence) Words() iter.Seq[string] {\n",
+    "\treturn strings.FieldsFuncSeq(s.text, notWord)\n",
+    "}\n",
+    "\n",
+    "// shortRepr mimics reprlib.repr for strings: quote the value, and\n",
+    "// if it's longer than maxLen runes, replace the middle with \"…\".\n",
+    "func shortRepr(s string, maxLen int) string {\n",
+    "\tif utf8.RuneCountInString(s) <= maxLen {\n",
+    "\t\treturn fmt.Sprintf(\"%s\", s)\n",
+    "\t}\n",
+    "\trunes := []rune(s)\n",
+    "\thead := string(runes[:maxLen/2])\n",
+    "\ttail := string(runes[len(runes)-maxLen/2:])\n",
+    "\treturn fmt.Sprintf(\"%s\", head+\"…\"+tail)\n",
+    "}"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "id": "1ae93130-4875-4e81-84d2-9b44b0834adc",
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "{The time has come to speak of many things}\n",
+      "main.Sentence\tmain.Sentence{text:\"The time has come to speak of many things\"}\n",
+      "The\n",
+      "time\n",
+      "has\n",
+      "come\n",
+      "to\n",
+      "speak\n",
+      "of\n",
+      "many\n",
+      "things\n"
+     ]
+    }
+   ],
+   "source": [
+    "%%\n",
+    "s := Sentence{\"The time has come to speak of many things\"}\n",
+    " \n",
+    "fmt.Println(s) // calls Sentence.String() via the Stringer interface\n",
+    "fmt.Printf(\"%T\\t%#v\\n\", s, s)\n",
+    "\n",
+    "for word := range s.Words() {\n",
+    "    fmt.Println(word)\n",
+    "}"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "id": "5db65ffb-c7d0-4346-8785-158b659f6fd4",
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "main.Sentence\tmain.Sentence{text:\"\\\"The time has c…f many things:\\\"\"}"
+     ]
+    }
+   ],
+   "source": [
+    "%%\n",
+    "s := Sentence{`\"The time has c…f many things:\"`}\n",
+    "fmt.Printf(\"%T\\t%#v\", s, s)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "77d101ce-6220-45ad-a369-ca64beae0d9e",
+   "metadata": {},
+   "outputs": [],
+   "source": []
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Go (gonb)",
+   "language": "go",
+   "name": "gonb"
+  },
+  "language_info": {
+   "codemirror_mode": "",
+   "file_extension": ".go",
+   "mimetype": "text/x-go",
+   "name": "go",
+   "nbconvert_exporter": "",
+   "pygments_lexer": "",
+   "version": "go1.25.8"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}