span class="c1">// Sign has the agent sign the data using a protocol 2 key as defined in
</span><span class="c1"></span>	<span class="c1">// [PROTOCOL.agent] section 3.6. This method is also implemented in
</span><span class="c1"></span>	<span class="c1">// [ssh.Signer] interface.
</span><span class="c1"></span>	<span id="Agent.Sign"><span class="nf">Sign</span></span><span class="p">(</span><span class="nx">key</span> <a href=".."><span class="nx">ssh</span></a><span class="p">.</span><a href="..#PublicKey