s, 2];</code></pre>
<p>The key is understanding that a single index always reduces
dimensionality, whereas a multiple index never does. The dimensions
with multiple indexes (and unindexed dimensions) determine the indexed
expression’s type. In the example above, because <code>v</code> is an array
of vectors, <code>v[2, idxs]</code> reduces the array dimension but doesn’t
reduce the vector dimension, so the result is a vector. In contrast,
<code>v[idxs, 2]</code> does not reduce the array dimension, but 