title: python, numpy; How to insert element at the start of an array
body: <p>I have an numpy array of complex numbers. So I want to insert zero at start of the array,
  and shift the rest of the array one place forward. <br></p>
  
  <p>example: <br></p>
  
  <pre><code>a = [1 + 2j, 5 + 7j,..]
  </code></pre>
  
  <p>I want to make:</p>
  
  <pre><code>a = [0 + 0j, 1 + 2j, 5 + 7j,..]
  </code></pre>
  
  <p>What's the simplest way to do this?</p>