title: Insert_after() function of BeautifulSoup4 works unexpectidly
body: <p>I want to use insert_after() function of bs4 but I can't understand why in this case it inserts <b></b> only after the second  tag? Why not after each one? If I change code to insert for example some text instead of  tag, it inserts it after each link.</p>
  
  <pre><code>from bs4 import BeautifulSoup
  soup = BeautifulSoup('&lt;p&gt;&lt;a href="http://www.foo.com"&gt;this if foo&lt;/a&gt;&lt;a href="http://www.bar.com"&gt;this if bar&lt;/a&gt;&lt;/p&gt;')
  b = soup.new_tag('b')
  for link_tag in soup.findAll('a'):
      link_tag.insert_after(b)
  print soup
  </code></pre>
  
  <p>Output:</p>
  
  <pre><code>&lt;html&gt;
      &lt;p&gt;
        &lt;a href="http://www.foo.com"&gt;
          this if foo
        &lt;/a&gt;
        &lt;a href="http://www.bar.com"&gt;
          this if bar
        &lt;/a&gt;
        &lt;b&gt;
        &lt;/b&gt;
      &lt;/p&gt;
    &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>Could you please explain to me how I can use this function to insert after each  tag?</p>