Check if one vector contains at least one value from another vector
<p>If I have two vectors:</p>

<pre><code>(def moo [:a :b :c :d])

(def foo [:a :z :d :e :f :g])
</code></pre>

<p>what is the easiest (canonical) way to check whether moo contains at least one value which is also in foo. In this case it would return 'true' because :a and :d appear in foo.</p>

<p>And secondly: Is it possible to refine this further to return true iff foo contains all elements of moo (but is allowed to contain others as well)</p>