call out optional second argument to split()

strings.html

@@ -261,8 +261,8 @@ experience of years.</samp>
 <samp class=pp>{'password': 'PapayaWhip', 'user': 'pilgrim', 'database': 'master'}</samp></pre>
 
 <ol>
-<li>The <code><dfn>split</dfn>()</code> string method takes one argument, a delimiter, and splits a string into a list of strings based on the delimiter. Here, the delimiter is an ampersand character, but it could be anything.
-<li>Now we have a list of strings, each with a key, followed by an equals sign, followed by a value. We can use a <a href=comprehensions.html#listcomprehension>list comprehension</a> to iterate over the entire list and split each string into two strings based on the first equals sign. (In theory, a value could contain an equals sign too. If we just used <code>'key=value=foo'.split('=')</code>, we would end up with a three-item list <code>['key', 'value', 'foo']</code>.)
+<li>The <code><dfn>split</dfn>()</code> string method has one required argument, a delimiter. The method splits a string into a list of strings based on the delimiter. Here, the delimiter is an ampersand character, but it could be anything.
+<li>Now we have a list of strings, each with a key, followed by an equals sign, followed by a value. We can use a <a href=comprehensions.html#listcomprehension>list comprehension</a> to iterate over the entire list and split each string into two strings based on the first equals sign. The optional second argument to the <code>split()</code> method is the number of times you want to split. <code>1</code> means &#8220;only split once,&#8221; so the <code>split()</code> method will return a two-item list. (In theory, a value could contain an equals sign too. If you just used <code>'key=value=foo'.split('=')</code>, you would end up with a three-item list <code>['key', 'value', 'foo']</code>.)
 <li>Finally, Python can turn that list-of-lists into a dictionary simply by passing it to the <code>dict()</code> function.
 </ol>