ass="pre">dynamic_properties</span></tt>
object.  Furthermore, the code no longer makes reference to key or
value types: keys and values are represented with strings.
Nonetheless the function still uses non-string types where they are
useful.  For instance, Fred's old age is represented using an <tt class="docutils literal"><span class="pre">int</span></tt>.
It's value is retreived by calling <tt class="docutils literal"><span class="pre">get</span></tt> with a
type parameter, which determines its return ty