<p>File system API for Q when/defer-style promises</p>

<p>Open options:</p>

<ul>
<li><code>flags</code>: <code>r</code>, <code>w</code>, <code>a</code>, <code>b</code></li>
<li><code>charset</code>: default of <code>utf-8</code></li>
<li><code>bufferSize</code>: in bytes</li>
<li><code>mode</code>: UNIX permissions</li>
<li><code>begin</code> first byte to read (defaults to zero)</li>
<li><code>end</code> one past the last byte to read.  <code>end - begin == length</code></li>
</ul>

<p>Functions:</p>

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