title: Changing the list: A variable assigned to does not change the "id" of the variable for subsequent changes
body: <p>Is this as expected? I thought in Python, variables are pointers to objects in memory. If I modify the python list that a variable points to once, the memory reference changes. But if I modify it again, the memory reference is the same?</p>
  <pre><code>&gt;&gt;&gt; id(mylist)
  Traceback (most recent call last):
    File &quot;&lt;stdin&gt;&quot;, line 1, in &lt;module&gt;
  NameError: name 'mylist' is not defined
  &gt;&gt;&gt; mylist = [0]
  &gt;&gt;&gt; id(mylist)
  4417893152
  &gt;&gt;&gt; mylist = [0, 1]
  &gt;&gt;&gt; id(mylist)
  4418202992 # ID changes
  &gt;&gt;&gt; mylist.append(3)
  &gt;&gt;&gt; mylist
  [0, 1, 3]
  &gt;&gt;&gt; id(mylist)
  4418202992 # ID stays the same
  &gt;&gt;&gt; mylist.append(4)
  &gt;&gt;&gt; mylist
  [0, 1, 3, 4]
  &gt;&gt;&gt; id(mylist)
  4418202992 # ID stays the same
  &gt;&gt;&gt;
  </code></pre>