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Added an example of how to create non-blocking widget code
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Jonathan Frederic
parent
d795654251
commit
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217
examples/widgets/Nonblocking Console.ipynb
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217
examples/widgets/Nonblocking Console.ipynb
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{
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"metadata": {
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"name": ""
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},
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"nbformat": 3,
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"nbformat_minor": 0,
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"worksheets": [
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{
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"cells": [
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{
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"cell_type": "code",
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"collapsed": false,
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"input": [
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"from subprocess import Popen, PIPE\n",
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"import fcntl\n",
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"import os\n",
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"\n",
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"from IPython.html import widgets\n",
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"from IPython.display import display"
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],
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"language": "python",
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"metadata": {},
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"outputs": [],
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"prompt_number": 1
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"Create the output, input, and console toggle widgets."
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]
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},
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{
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"cell_type": "code",
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"collapsed": false,
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"input": [
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"console_container = widgets.ContainerWidget(visible=False)\n",
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"console_container.set_css('padding', '10px')\n",
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"\n",
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"console_style = {\n",
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" 'font-family': 'monospace',\n",
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" 'color': '#AAAAAA',\n",
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" 'background': 'black',\n",
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" 'width': '800px',\n",
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"}\n",
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"\n",
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"output_box = widgets.StringWidget(parent=console_container, default_view_name='TextAreaView')\n",
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"output_box.set_css(console_style)\n",
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"output_box.set_css('height', '400px')\n",
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"\n",
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"input_box = widgets.StringWidget(parent=console_container)\n",
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"input_box.set_css(console_style)\n",
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"\n",
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"toggle_button = widgets.ButtonWidget(description=\"Start Console\")\n",
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"def toggle_console():\n",
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" console_container.visible = not console_container.visible\n",
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" if console_container.visible:\n",
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" toggle_button.description=\"Stop Console\"\n",
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" input_box.disabled = False\n",
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" else:\n",
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" toggle_button.description=\"Start Console\"\n",
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"toggle_button.on_click(toggle_console)\n"
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],
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"language": "python",
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"metadata": {},
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"outputs": [],
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"prompt_number": 2
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"Define function to run a process without blocking the input."
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]
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},
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{
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"cell_type": "code",
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"collapsed": false,
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"input": [
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"def read_process(process, append_output):\n",
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" \"\"\" Try to read the stdout and stderr of a process and render it using \n",
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" the append_output method provided\n",
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" \n",
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" Parameters\n",
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" ----------\n",
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" process: Popen handle\n",
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" append_output: method handle\n",
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" Callback to render output. Signature of\n",
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" append_output(output, [prefix=])\"\"\"\n",
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" \n",
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" try:\n",
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" stdout = process.stdout.read()\n",
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" if stdout is not None and len(stdout) > 0:\n",
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" append_output(stdout)\n",
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" except:\n",
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" pass\n",
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" \n",
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" try:\n",
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" stderr = process.stderr.read()\n",
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" if stderr is not None and len(stderr) > 0:\n",
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" append_output(stderr, prefix='ERR ')\n",
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" except:\n",
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" pass\n",
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"\n",
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"\n",
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"def set_pipe_nonblocking(pipe):\n",
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" \"\"\"Set a pipe as non-blocking\"\"\"\n",
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" fl = fcntl.fcntl(pipe, fcntl.F_GETFL)\n",
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" fcntl.fcntl(pipe, fcntl.F_SETFL, fl | os.O_NONBLOCK)\n",
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"\n",
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"\n",
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"kernel = get_ipython().kernel\n",
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"def run_command(command, append_output, has_user_exited=None):\n",
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" \"\"\"Run a command asyncronously\n",
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" \n",
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" Parameters\n",
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" ----------\n",
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" command: str\n",
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" Shell command to launch a process with.\n",
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" append_output: method handle\n",
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" Callback to render output. Signature of\n",
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" append_output(output, [prefix=])\n",
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" has_user_exited: method handle\n",
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" Check to see if the user wants to stop the command.\n",
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" Must return a boolean.\"\"\"\n",
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" \n",
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" # Echo input.\n",
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" append_output(command, prefix='>>> ')\n",
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" \n",
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" # Create the process. Make sure the pipes are set as non-blocking.\n",
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" process = Popen(command, shell=True, stdout=PIPE, stderr=PIPE)\n",
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" set_pipe_nonblocking(process.stdout)\n",
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" set_pipe_nonblocking(process.stderr)\n",
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" \n",
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" # Only continue to read from the command \n",
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" while (has_user_exited is None or not has_user_exited()) and process.poll() is None:\n",
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" read_process(process, append_output)\n",
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" kernel.do_one_iteration() # Run IPython iteration. This is the code that\n",
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" # makes this operation non-blocking. This will\n",
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" # allow widget messages and callbacks to be \n",
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" # processed.\n",
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" \n",
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" # If the process is still running, the user must have exited.\n",
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" if process.poll() is None:\n",
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" process.kill()\n",
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" else:\n",
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" read_process(process, append_output) # Read remainer\n",
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" \n",
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" \n",
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" \n",
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" "
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],
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"language": "python",
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"metadata": {},
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"outputs": [],
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"prompt_number": 3
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"Hook the process execution methods up to our console widgets."
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]
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},
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{
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"cell_type": "code",
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"collapsed": false,
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"input": [
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"def append_output(output, prefix=' '):\n",
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" output_lines = output.split('\\n')\n",
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" formatted_output = '\\n'.join([prefix + line for line in output_lines if len(line) > 0]) + '\\n'\n",
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" output_box.value += formatted_output\n",
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" output_box.scroll_to_bottom()\n",
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" \n",
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"def has_user_exited():\n",
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" return not console_container.visible\n",
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"\n",
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"def handle_input(sender):\n",
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" sender.disabled = True\n",
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" try:\n",
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" command = sender.value\n",
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" sender.value = ''\n",
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" run_command(command, append_output=append_output, has_user_exited=has_user_exited)\n",
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" finally:\n",
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" sender.disabled = False\n",
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" \n",
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"input_box.on_submit(handle_input)"
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],
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"language": "python",
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"metadata": {},
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"outputs": [],
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"prompt_number": 4
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"Show the console"
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]
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},
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{
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"cell_type": "code",
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"collapsed": false,
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"input": [
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"display(toggle_button)\n",
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"display(console_container)"
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],
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"language": "python",
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"metadata": {},
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"outputs": [],
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"prompt_number": 5
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}
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],
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"metadata": {}
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}
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]
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}
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