def add_sec_label(cell: NotebookNode, nbname) -> Sequence[NotebookNode]:
    """Adds a Latex \\label{} under the chapter heading.

    This takes the first cell of a notebook, and expects it to be a Markdown
    cell starting with a level 1 heading. It inserts a label with the notebook
    name just underneath this heading.
    """
    assert cell.cell_type == 'markdown', cell.cell_type
    lines = cell.source.splitlines()
    if lines[0].startswith('# '):
        header_lines = 1
    elif len(lines) > 1 and lines[1].startswith('==='):
        header_lines = 2
    else:
        raise NoHeader

    header = '\n'.join(lines[:header_lines])
    intro_remainder = '\n'.join(lines[header_lines:]).strip()
    res = [
        new_markdown_cell(header),
        new_latex_cell('\label{sec:%s}' % nbname)
    ]
    res[0].metadata = cell.metadata
    if intro_remainder:
        res.append(new_markdown_cell(intro_remainder))
    return res

def test_preprocessor_collapsible_headings():
    """Test collapsible_headings preprocessor."""
    # check import shortcut
    from jupyter_contrib_nbextensions.nbconvert_support import CollapsibleHeadingsPreprocessor  # noqa
    cells = []
    for lvl in range(6, 1, -1):
        for collapsed in (True, False):
            cells.extend([
                nbf.new_markdown_cell(
                    source='{} {} heading level {}'.format(
                        '#' * lvl,
                        'Collapsed' if collapsed else 'Uncollapsed',
                        lvl),
                    metadata={'heading_collapsed': True} if collapsed else {}),
                nbf.new_markdown_cell(source='\n'.join([
                    'want hidden' if collapsed else 'want to see',
                    'what I mean',
                ])),
                nbf.new_code_cell(source='\n'.join([
                    'want hidden' if collapsed else 'want to see',
                    'what I mean',
                ])),
            ])
    notebook_node = nbf.new_notebook(cells=cells)
    body, resources = export_through_preprocessor(
        notebook_node, CollapsibleHeadingsPreprocessor, RSTExporter, 'rst')
    assert_not_in('hidden', body, 'check text hidden by collapsed headings')
    assert_in('want to see', body, 'check for text under uncollapsed headings')

 def test_html_collapsible_headings(self):
     """Test exporter for inlining collapsible_headings"""
     nb = v4.new_notebook(cells=[
         v4.new_markdown_cell(source=('# level 1 heading')),
         v4.new_code_cell(source='a = range(1,10)'),
         v4.new_markdown_cell(source=('## level 2 heading')),
         v4.new_code_cell(source='a = range(1,10)'),
         v4.new_markdown_cell(source=('### level 3 heading')),
         v4.new_code_cell(source='a = range(1,10)'),
     ])
     self.check_stuff_gets_embedded(
         nb, 'html_ch', to_be_included=['collapsible_headings'])

    def test_html_collapsible_headings(self):
        """Test exporter for inlining collapsible_headings"""
        nb = v4.new_notebook(cells=[
            v4.new_markdown_cell(source=('# level 1 heading')),
            v4.new_code_cell(source='a = range(1,10)'),
            v4.new_markdown_cell(source=('## level 2 heading')),
            v4.new_code_cell(source='a = range(1,10)'),
            v4.new_markdown_cell(source=('### level 3 heading')),
            v4.new_code_cell(source='a = range(1,10)'),
        ])

        def check(byte_string, root_node):
            assert b'collapsible_headings' in byte_string

        self.check_html(nb, 'html_ch', check_func=check)

    def build_notebook(self):
        """Build a reveal slides notebook in memory for use with tests.
        Overrides base in PreprocessorTestsBase"""

        outputs = [nbformat.new_output(output_type="stream", name="stdout", text="a")]

        slide_metadata = {'slideshow' : {'slide_type': 'slide'}}
        subslide_metadata = {'slideshow' : {'slide_type': 'subslide'}}

        cells=[nbformat.new_code_cell(source="", execution_count=1, outputs=outputs),
               nbformat.new_markdown_cell(source="", metadata=slide_metadata),
               nbformat.new_code_cell(source="", execution_count=2, outputs=outputs),
               nbformat.new_markdown_cell(source="", metadata=slide_metadata),
               nbformat.new_markdown_cell(source="", metadata=subslide_metadata)]

        return nbformat.new_notebook(cells=cells)

    def test_very_long_cells(self):
        """
        Torture test that long cells do not cause issues
        """
        lorem_ipsum_text = textwrap.dedent("""\
          Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec
          dignissim, ipsum non facilisis tempus, dui felis tincidunt metus,
          nec pulvinar neque odio eget risus. Nulla nisi lectus, cursus
          suscipit interdum at, ultrices sit amet orci. Mauris facilisis
          imperdiet elit, vitae scelerisque ipsum dignissim non. Integer
          consequat malesuada neque sit amet pulvinar. Curabitur pretium
          ut turpis eget aliquet. Maecenas sagittis lacus sed lectus
          volutpat, eu adipiscing purus pulvinar. Maecenas consequat
          luctus urna, eget cursus quam mollis a. Aliquam vitae ornare
          erat, non hendrerit urna. Sed eu diam nec massa egestas pharetra
          at nec tellus. Fusce feugiat lacus quis urna sollicitudin volutpat.
          Quisque at sapien non nibh feugiat tempus ac ultricies purus.
           """)
        lorem_ipsum_text = lorem_ipsum_text.replace("\n"," ") + "\n\n"
        large_lorem_ipsum_text = "".join([lorem_ipsum_text]*3000)

        notebook_name = "lorem_ipsum_long.ipynb"
        nb = v4.new_notebook(
            cells=[
                    v4.new_markdown_cell(source=large_lorem_ipsum_text)
            ]
        )

        with TemporaryDirectory() as td:
            nbfile = os.path.join(td, notebook_name)
            with open(nbfile, 'w') as f:
                write(nb, f, 4)

            (output, resources) = LatexExporter(template_file='article').from_filename(nbfile)
            assert len(output) > 0

    def test_checkpoints_follow_file(self):

        # Read initial file state
        orig = self.api.read('foo/a.ipynb')

        # Create a checkpoint of initial state
        r = self.api.new_checkpoint('foo/a.ipynb')
        cp1 = r.json()

        # Modify file and save
        nbcontent = json.loads(orig.text)['content']
        nb = from_dict(nbcontent)
        hcell = new_markdown_cell('Created by test')
        nb.cells.append(hcell)
        nbmodel = {'content': nb, 'type': 'notebook'}
        self.api.save('foo/a.ipynb', body=json.dumps(nbmodel))

        # Rename the file.
        self.api.rename('foo/a.ipynb', 'foo/z.ipynb')

        # Looking for checkpoints in the old location should yield no results.
        self.assertEqual(self.api.get_checkpoints('foo/a.ipynb').json(), [])

        # Looking for checkpoints in the new location should work.
        cps = self.api.get_checkpoints('foo/z.ipynb').json()
        self.assertEqual(cps, [cp1])

        # Delete the file.  The checkpoint should be deleted as well.
        self.api.delete('foo/z.ipynb')
        cps = self.api.get_checkpoints('foo/z.ipynb').json()
        self.assertEqual(cps, [])

def add_statistics(plan, file):
    cells = [nbf.new_markdown_cell('# Viajes correctos vs Incidencias\n## Se reportaron viajes para el plan: {}'.format(plan)),
             nbf.new_code_cell('show(f)'),
             nbf.new_code_cell('msj_estadisticaplan(\'{}\', viajes)'.format(plan)),
             nbf.new_markdown_cell('# Plan {} de distribución (Sin Modificaciones)'.format(plan)),
             nbf.new_code_cell('an.getkm(\'plan\', \'{}\')'.format(plan)),
             nbf.new_code_cell('geojsonio.embed(an.gettrips(\'plan\', \'{}\').to_geojson())'.format(plan)),
             nbf.new_markdown_cell('# Plan {} Modificado'.format(plan)),
             nbf.new_code_cell('an.getkm(\'planm\', \'{}\')'.format(plan)),
             nbf.new_code_cell('geojsonio.embed(an.gettrips(\'planm\', \'{}\').to_geojson())'.format(plan)),
            ]
    noto = json.load(open(file))
    noto['cells'] = noto['cells'] + cells

    with open(file, 'w') as f:
        json.dump(noto, f)

    def setUp(self):
        nbdir = self.notebook_dir
        
        if not os.path.isdir(pjoin(nbdir, 'foo')):
            subdir = pjoin(nbdir, 'foo')

            os.mkdir(subdir)

            # Make sure that we clean this up when we're done.
            # By using addCleanup this will happen correctly even if we fail
            # later in setUp.
            @self.addCleanup
            def cleanup_dir():
                shutil.rmtree(subdir, ignore_errors=True)

        nb = new_notebook()
        
        nb.cells.append(new_markdown_cell(u'Created by test ³'))
        cc1 = new_code_cell(source=u'print(2*6)')
        cc1.outputs.append(new_output(output_type="stream", text=u'12'))
        cc1.outputs.append(new_output(output_type="execute_result",
            data={'image/png' : png_green_pixel},
            execution_count=1,
        ))
        nb.cells.append(cc1)
        
        with io.open(pjoin(nbdir, 'foo', 'testnb.ipynb'), 'w',
                     encoding='utf-8') as f:
            write(nb, f, version=4)

        self.nbconvert_api = NbconvertAPI(self.request)

    def build_notebook(self, with_json_outputs=False):
        """Build a notebook in memory for use with preprocessor tests"""

        outputs = [
            nbformat.new_output("stream", name="stdout", text="a"),
            nbformat.new_output("display_data", data={'text/plain': 'b'}),
            nbformat.new_output("stream", name="stdout", text="c"),
            nbformat.new_output("stream", name="stdout", text="d"),
            nbformat.new_output("stream", name="stderr", text="e"),
            nbformat.new_output("stream", name="stderr", text="f"),
            nbformat.new_output("display_data", data={'image/png': 'Zw=='}), # g
            nbformat.new_output("display_data", data={'application/pdf': 'aA=='}), # h
        ]
        if with_json_outputs:
            outputs.extend([
                nbformat.new_output(
                    "display_data", data={'application/json': [1, 2, 3]}
                ), # j
                nbformat.new_output(
                    "display_data", data={'application/json': {'a': 1, 'c': {'b': 2}}}
                ), # k
                nbformat.new_output(
                    "display_data", data={'application/json': 'abc'}
                ), # l
                nbformat.new_output(
                    "display_data", data={'application/json': 15.03}
                ), # m
            ])

        cells=[nbformat.new_code_cell(source="$ e $", execution_count=1, outputs=outputs),
               nbformat.new_markdown_cell(source="$ e $")]

        return nbformat.new_notebook(cells=cells)

 def test_htmltoc2(self):
     """Test exporter for adding table of contents"""
     nb = v4.new_notebook(cells=[
         v4.new_code_cell(source="a = 'world'"),
         v4.new_markdown_cell(source="# Heading"),
     ])
     self.check_stuff_gets_embedded(
         nb, 'html_toc', to_be_included=['toc2'])

    def add_markdown_cell(self, path):
        # Load and update
        model = self.contents.get(path=path)
        model['content'].cells.append(
            new_markdown_cell('Created by test: ' + path)
        )

        # Save and checkpoint again.
        self.contents.save(model, path=path)
        return model

 def test_embedhtml(self):
     """Test exporter for embedding images into HTML"""
     nb = v4.new_notebook(cells=[
         v4.new_code_cell(source="a = 'world'"),
         v4.new_markdown_cell(
             source="![testimage]({})".format(path_in_data('icon.png'))
         ),
     ])
     self.check_stuff_gets_embedded(
         nb, 'html_embed', to_be_included=['base64'])

    def test_htmltoc2(self):
        """Test exporter for adding table of contents"""
        with self.create_temp_cwd():
            nb = v4.new_notebook(
                cells=[v4.new_code_cell(source="a = 'world'"), v4.new_markdown_cell(source="# Heading")]
            )
            with io.open("notebook2.ipynb", "w", encoding="utf-8") as f:
                write(nb, f, 4)

            self.nbconvert("--to html_toc" ' "notebook2"')
            assert os.path.isfile("notebook2.html")

    def build_notebook(self):
        notebook = super(TestRegexRemove, self).build_notebook()
        # Add a few empty cells
        notebook.cells.extend([
            nbformat.new_code_cell(''),
            nbformat.new_markdown_cell(' '),
            nbformat.new_raw_cell('\n'),
            nbformat.new_raw_cell('\t'),
        ])

        return notebook

    def test_htmltoc2(self):
        """Test exporter for adding table of contents"""
        nb = v4.new_notebook(cells=[
            v4.new_code_cell(source="a = 'world'"),
            v4.new_markdown_cell(source="# Heading"),
        ])

        def check(byte_string, root_node):
            assert b'toc2' in byte_string

        self.check_html(nb, 'html_toc', check_func=check)

def test_present_markdown_cell():
    cell = v4.new_markdown_cell(source='# Heading\n\n*some markdown*')
    lines = pp.present_value('+ ', cell)
    text = '\n'.join(lines)
    assert lines[0] == ''
    assert lines[1] == '+ markdown cell:'
    assert all(line.startswith('+ ') for line in lines if line)
    assert 'source:' in text
    assert '# Heading' in text
    assert '' in lines
    assert '*some markdown*' in text

def test_add_sec_label():
    sample = ("# Foo\n"
              "\n"
              "Bar")
    res = latex.add_sec_label(new_markdown_cell(sample), '05-test')
    assert len(res) == 3
    assert res[0].cell_type == 'markdown'
    assert res[0].source.strip() == '# Foo'
    assert res[1].cell_type == 'raw'
    assert res[1].source.strip() == '\\label{sec:05-test}'
    assert res[2].cell_type == 'markdown'

    sample = ("Foo\n"
              "===\n")
    res = latex.add_sec_label(new_markdown_cell(sample), '05-test')
    assert len(res) == 2
    assert res[0].cell_type == 'markdown'
    assert res[0].source.strip() == 'Foo\n==='
    assert res[1].cell_type == 'raw'
    assert res[1].source.strip() == '\\label{sec:05-test}'

def parseBkr(data):
    nb = new_notebook()
    evaluators = list((cell['evaluator']) for cell in data['cells'] if 'evaluator' in cell)
    kernel_name = max(evaluators, key=evaluators.count) if evaluators else 'IPython'
    if kernel_name in ['JavaScript', 'HTML', 'TeX']:
        kernel_name = 'IPython'
    if kernel_name == 'IPython':
        kernel_spec = {"kernelspec": {
            "display_name": "Python 2",
            "language": "python",
            "name": "python2"
        }}
    else:
        kernel_spec = {"kernelspec": {
            "display_name": kernel_name,
            "language": kernel_name.lower(),
            "name": kernel_name.lower()
        }}
    nb.metadata = kernel_spec
    for cell in data['cells']:
        if cell['type'] == 'code':
            metadata = {}
            if 'initialization' in cell:
                metadata['init_cell'] = True
            if 'tags' in cell:
                tags = [cell['tags']]
                metadata['tags'] = tags
            if cell['evaluator'] != kernel_name:
                if cell['evaluator'] == 'TeX':
                    nb.cells.append(new_markdown_cell("${0}$".format(getFixedCodeText(cell['input']))))
                else:
                    nb.cells.append(
                        new_code_cell(source='%%{0}\n{1}'.format(cell['evaluator'].lower(), getFixedCodeText(cell['input'])),
                                      metadata=metadata))
            else:
                nb.cells.append(new_code_cell(source=getFixedCodeText(cell['input']), metadata=metadata))
        if cell['type'] == 'markdown':
            nb.cells.append(new_markdown_cell(getFixedCodeText(cell)))
        if cell['type'] == 'section':
            nb.cells.append(new_markdown_cell(setHeader(cell['level'], cell['title'])))
    return nb

def lines_to_notebook(lines, name=None):
    """
    Convert the lines of an m file into an IPython notebook

    Parameters
    ----------
    lines : list
        A list of strings. Each element is a line in the m file

    Returns
    -------
    notebook : an IPython NotebookNode class instance, containing the
    information required to create a file


    """
    source = []
    md = np.empty(len(lines), dtype=object)
    new_cell = np.empty(len(lines), dtype=object)
    for idx, l in enumerate(lines):
        new_cell[idx], md[idx], this_source = format_line(l)
        # Transitions between markdown and code and vice-versa merit a new
        # cell, even if no newline, or "%%" is found. Make sure not to do this
        # check for the very first line!
        if idx>1 and not new_cell[idx]:
            if md[idx] != md[idx-1]:
                new_cell[idx] = True

        source.append(this_source)
    # This defines the breaking points between cells:
    new_cell_idx = np.hstack([np.where(new_cell)[0], -1])

    # Listify the sources:
    cell_source = [source[new_cell_idx[i]:new_cell_idx[i+1]]
                   for i in range(len(new_cell_idx)-1)]
    cell_md = [md[new_cell_idx[i]] for i in range(len(new_cell_idx)-1)]
    cells = []

    # Append the notebook with loading matlab magic extension
    notebook_head = "import pymatbridge as pymat\n" + "ip = get_ipython()\n" \
                    + "pymat.load_ipython_extension(ip)"
    cells.append(nbformat.new_code_cell(notebook_head))#, language='python'))

    for cell_idx, cell_s in enumerate(cell_source):
        if cell_md[cell_idx]:
            cells.append(nbformat.new_markdown_cell(cell_s))
        else:
            cell_s.insert(0, '%%matlab\n')
            cells.append(nbformat.new_code_cell(cell_s))#, language='matlab'))

    #ws = nbformat.new_worksheet(cells=cells)
    notebook = nbformat.new_notebook(cells=cells)
    return notebook