title: Adding named item to named list - guaranteed to append to end of list?
body: <p>When adding a named item to a list, is it guaranteed that the item will be added to the end of the list?  In practice it appears to be the case, but not sure if this is a dangerous assumption?</p>
  
  <pre><code>test = list()
  test[[ "one" ]] = 1
  test[[ "two" ]] = 2  # will always appear after "one"?
  test[[ "three" ]] = 3  # will always appear after "two"?
  </code></pre>