title: Edit XML value based on Key
body: <p>Using beautifulsoup 4, how do I edit a value based on a name?  Given I know name = "foo" (constant and unique), how do I read the value "bar" (unknown at runtime), and change it to a new string, "baz"? </p>
  
  <p>I can read the line using soup.find_all(text="foo"), but I can't figure out how to conveniently read the value, or change the string "bar" --> "baz"</p>
  
  <p>XML Excerpt: </p>
  
  <pre><code>&lt;djmacros&gt;
    &lt;macro name="foo" value="bar"&gt;
      &lt;description&gt;foobar&lt;/description&gt;
    &lt;/macro&gt;
  &lt;/djmacros&gt;
  </code></pre>