shared manner, which makes them no
longer live. Live owned references have the unique property that they can be
moved out of (though mutable references <em>can</em> be swapped out of). This power is
only given to <em>live</em> owned references because moving its referent would of
course invalidate all outstanding references prematurely.</p>

<p>As a local lint against inappropriate mutation, only variables that are marked
as <code>mut</code> can be borrowed mutably.</p>

<p>It is interesting to note that Bo