e. the direction of the
curve at <a href="../../dart-ui/Tangent/position.html">position</a>).</p>
<p>This value is in radians, with 0.0 meaning pointing along the x axis in
the positive x-axis direction, positive numbers pointing downward toward
the negative y-axis, i.e. in a clockwise direction, and negative numbers
pointing upward toward the positive y-axis, i.e. in a counter-clockwise
direction.</p>
        </section>
                <section class="summary source-code" id="source">
          <h2><span>I