observer</span><span class="token punctuation">(</span><span class="token string">'salutation'</span><span class="token punctuation">,</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
    <span class="token comment">// some side effect of salutation changing</span>
  <span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
