How to use the soupsieve.select_one function in soupsieve

"""Test match parent closest."""

        markup = """
        <article id="article">
          <div id="div-01">Here is div-01
            <div id="div-02">Here is div-02
              <div id="div-04">Here is div-04</div>
              <div id="div-03">Here is div-03</div>
            </div>
            <div id="div-05">Here is div-05</div>
          </div>
        </article>
        """

        soup = self.soup(markup, 'html.parser')
        el = sv.select_one('#div-03', soup)
        self.assertTrue(sv.closest('#div-02', el).attrs['id'] == 'div-02')

<p id="1"><code id="2"></code><img src="./image.png" id="3"></p>
        <pre id="4"></pre>
        <p><span class="some-class" id="5"></span><span id="some-id"></span></p>
        <pre class="ignore" id="6">            
        </pre>
        
        
        """

        soup = self.soup(markup, 'html.parser')
        self.assertEqual(None, sv.select_one('h1', soup))

"""Test closest match complex parent."""

        markup = """
        <article id="article">
          <div id="div-01">Here is div-01
            <div id="div-02">Here is div-02
              <div id="div-04">Here is div-04</div>
              <div id="div-03">Here is div-03</div>
            </div>
            <div id="div-05">Here is div-05</div>
          </div>
        </article>
        """

        soup = self.soup(markup, 'html.parser')
        el = sv.select_one('#div-03', soup)
        self.assertTrue(sv.closest('article &gt; div', el).attrs['id'] == 'div-01')
        self.assertTrue(sv.closest(':not(div)', el).attrs['id'] == 'article')

<p id="1"><code id="2"></code><img src="./image.png" id="3"></p>
        <pre id="4"></pre>
        <p><span class="some-class" id="5"></span><span id="some-id"></span></p>
        <pre class="ignore" id="6">            
        </pre>
        
        
        """

        soup = self.soup(markup, 'html.parser')
        self.assertEqual(
            sv.select('span[id]', soup, limit=1)[0].attrs['id'],
            sv.select_one('span[id]', soup).attrs['id']
        )

"""Test closest."""

        markup = """
        <article id="article">
          <div id="div-01">Here is div-01
            <div id="div-02">Here is div-02
              <div id="div-04">Here is div-04</div>
              <div id="div-03">Here is div-03</div>
            </div>
            <div id="div-05">Here is div-05</div>
          </div>
        </article>
        """

        soup = bs4.BeautifulSoup(markup, 'html5lib')
        el = sv.select_one('#div-03', soup)

        self.assertTrue(sv.closest('#div-02', el).attrs['id'] == 'div-02')
        self.assertTrue(sv.closest('div div', el).attrs['id'] == 'div-03')
        self.assertTrue(sv.closest('article &gt; div', el).attrs['id'] == 'div-01')
        self.assertTrue(sv.closest(':not(div)', el).attrs['id'] == 'article')
        self.assertTrue(sv.closest('div #div-05', el) is None)
        self.assertTrue(sv.closest('a', el) is None)

soup = bs4.BeautifulSoup(markup, 'html5lib')
        ids = []
        for el in sv.select('span[id]', soup):
            ids.append(el.attrs['id'])

        self.assertEqual(sorted(['5', 'some-id']), sorted(ids))

        ids = []
        for el in sv.select('span[id]', soup, limit=1):
            ids.append(el.attrs['id'])

        self.assertEqual(sorted(['5']), sorted(ids))

        self.assertEqual(
            sv.select('span[id]', soup, limit=1)[0].attrs['id'],
            sv.select_one('span[id]', soup).attrs['id']
        )

        self.assertEqual(None, sv.select_one('h1', soup))

        ids = []
        for el in sv.iselect('span[id]', soup):
            ids.append(el.attrs['id'])

        self.assertEqual(sorted(['5', 'some-id']), sorted(ids))

        span = sv.select('span[id]', soup)[0]
        ids = []
        for el in sv.select('span[id]:not(#some-id)', span.parent):
            ids.append(el.attrs['id'])

        self.assertEqual(sorted(['5']), sorted(ids))

"""Test closest match self."""

        markup = """
        <article id="article">
          <div id="div-01">Here is div-01
            <div id="div-02">Here is div-02
              <div id="div-04">Here is div-04</div>
              <div id="div-03">Here is div-03</div>
            </div>
            <div id="div-05">Here is div-05</div>
          </div>
        </article>
        """

        soup = self.soup(markup, 'html.parser')
        el = sv.select_one('#div-03', soup)
        self.assertTrue(sv.closest('div div', el).attrs['id'] == 'div-03')

"""Test that closest only matches parents or self."""

        markup = """
        <article id="article">
          <div id="div-01">Here is div-01
            <div id="div-02">Here is div-02
              <div id="div-04">Here is div-04</div>
              <div id="div-03">Here is div-03</div>
            </div>
            <div id="div-05">Here is div-05</div>
          </div>
        </article>
        """

        soup = self.soup(markup, 'html.parser')
        el = sv.select_one('#div-03', soup)
        self.assertTrue(sv.closest('div #div-05', el) is None)
        self.assertTrue(sv.closest('a', el) is None)