returning <code>b</code> (or something equivalent to <code>b</code>), and values in between
meaning that the interpolation is at the relevant point on the timeline
between <code>a</code> and <code>b</code>. The interpolation can be extrapolated beyond 0.0 and
1.0, so negative values and values greater than 1.0 are valid (and can
easily be generated by curves such as <code>Curves.elasticInOut</code>).</p>
<p>Values for <code>t</code> are usually obtained from an <code>Animation&lt;double&gt;</code>, such as
