title: How to use any() to test if two arrays overlap
body: <p>I want to test if two arrays have common elements. I tried this but it does not work.</p>
  
  <pre><code>a = np.array([4,5])
  b = np.array([1,-1])
  a.any() in b
  </code></pre>
  
  <p>And this returns <code>True</code>...</p>