 an offset that is subtracted
from the breaks. The offset must be between <code>0</code> and the bin width.</p></li>
<li><p>A function taking a sorted vector of <code>breaks</code> (bin edges) and
returning an offset to subtract from the breaks.</p></li>
<li><p>A string giving the suffix of a function that starts with
<code>"align_"</code> used to determine the alignment, such as <code><a href="align.html">align_none()</a></code>,
<code><a href="align.html">align_boundary()</a></code>, or <code><a href="ali