 object <var>X</var> to the destination <var>D</var>.
</p>
<p><code>write_data</code> writes a matrix in row-major order,
with one line per row.
</p>
<p><code>write_data</code> writes an array created by <code>array</code> or <code>make_array</code>
in row-major order, with a new line at the end of every slab.
Higher-dimensional slabs are separated by additional new lines.
</p>
<p><code>write_data</code> writes a hashed array with each key followed by
its associated list on one line.
</p>
<p><code>write_dat