2022-03-21 12:07:02 +01:00
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"name": "#%% md\n"
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"source": [
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"_Aufgabe 1_\n",
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"\n",
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"Schreiben Sie eine Funktion <code>get_it_or_none1</code>, die ein Dictionary und einen\n",
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"Schlüsselwert als Parameter erhält. Sie soll den im Dictionary gespeicherten Wert\n",
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"zurückgeben, wenn er enthalten ist, andernfalls <code>None</code>.\n",
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"\n",
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"Vermeiden Sie bei der Implementierung das Auftreten einer Exception, indem Sie vor\n",
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"dem Zugriff prüfen, ob der Schlüssel enthalten ist."
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]
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"slide_type": "slide"
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},
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"outputs": [],
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"source": []
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"slideshow": {
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"slide_type": "slide"
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}
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},
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"outputs": [],
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"source": [
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"def get_it_or_none1(dict_arg, key):\n",
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" if key in dict_arg:\n",
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" return dict_arg[key]\n",
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" else:\n",
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" return None\n",
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" \n",
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"my_dict = {'a': 1, 2: 'b'}\n",
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"print(get_it_or_none1(my_dict, 'a'))\n",
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"print(get_it_or_none1(my_dict, 'b'))"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {
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"slideshow": {
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"slide_type": "slide"
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}
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},
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"source": [
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"_Aufgabe 2_\n",
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"\n",
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"Implementieren Sie eine Funktion <code>get_it_or_none2</code> mit der gleichen\n",
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"Funktionalität. Allerdings verzichten Sie dieses Mal auf die Prüfung und Fangen\n",
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"eine evtl. auftretende Exception, um dann <code>None</code> zurückzugeben."
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"slideshow": {
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"slide_type": "slide"
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}
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},
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"outputs": [],
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"source": []
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"pycharm": {
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"name": "#%%\n"
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},
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"slideshow": {
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"slide_type": "slide"
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}
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},
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"outputs": [],
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"source": [
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"def get_it_or_none2(dict_arg, key):\n",
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" try:\n",
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" return dict_arg[key]\n",
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" except:\n",
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" return None\n",
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" \n",
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"my_dict = {'a': 1, 2: 'b'}\n",
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"print(get_it_or_none2(my_dict, 'a'))\n",
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"print(get_it_or_none2(my_dict, 'b'))"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {
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"slideshow": {
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"slide_type": "slide"
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}
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},
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"source": [
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"_Aufgabe 3_\n",
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"\n",
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"Überprüfen Sie die Laufzeit der beiden Varianten, indem Sie jede Funktion\n",
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"10000-mal so aufrufen, dass <code>None</code> zurückgegeben wird. Was ist schneller?"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"slideshow": {
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"slide_type": "slide"
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}
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},
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"outputs": [],
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"source": [
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"import timeit\n"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"pycharm": {
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"name": "#%%\n"
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},
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"slideshow": {
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"slide_type": "slide"
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}
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},
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"outputs": [],
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"source": [
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"import timeit\n",
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"\n",
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"my_dict = {}\n",
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2022-05-12 08:46:17 +02:00
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"print(f'get_it_or_none1:: {timeit.timeit(lambda: get_it_or_none1(my_dict, 0), number=10000)}')\n",
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"print(f'get_it_or_none2:: {timeit.timeit(lambda: get_it_or_none2(my_dict, 0), number=10000)}')\n"
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2022-03-21 12:07:02 +01:00
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {
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"slideshow": {
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"slide_type": "slide"
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}
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},
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"source": [
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"_Aufgabe 4_\n",
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"\n",
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"Tatsächlich besitzt ein Python-Dictionary eine bisher nicht eingeführte Methode\n",
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"<code>get</code>, der neben dem Schlüssel auch ein Default-Wert übergeben werden kann,\n",
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"der zurückgegeben wird, wenn der Schlüssel nicht enthalten ist.\n",
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"\n",
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"<code>dict.get( \\< key \\>, \\< default \\> ) </code>\n",
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"\n",
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"Überprüfen Sie auch die Laufzeit dieses Ansatzes."
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"pycharm": {
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"name": "#%%\n"
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},
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"slideshow": {
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"slide_type": "slide"
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}
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},
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"outputs": [],
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"source": []
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {
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"slideshow": {
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"slide_type": "slide"
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}
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},
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"outputs": [],
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"source": [
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2022-05-12 08:46:17 +02:00
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"print(f'get_it_or_none2:: {timeit.timeit(lambda: my_dict.get(0), number=10000)}')\n"
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2022-03-21 12:07:02 +01:00
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {
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"slideshow": {
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"slide_type": "slide"
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}
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},
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"source": [
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"Wie erklären Sie sich die Ergebnisse?"
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]
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}
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],
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"metadata": {
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"celltoolbar": "Slideshow",
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"display_name": "Python 3 (ipykernel)",
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"language": "python",
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"name": "python3"
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},
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"language_info": {
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"codemirror_mode": {
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"name": "ipython",
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"version": 3
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},
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"file_extension": ".py",
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"mimetype": "text/x-python",
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"name": "python",
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"nbconvert_exporter": "python",
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"pygments_lexer": "ipython3",
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"version": "3.9.9"
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}
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"nbformat": 4,
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