title: How can I check whether the numpy array exists already or not?
body: <p>I want to know if an array is already defined somewhere before in the code.
  Something like <code>a.exist()</code> gives True if it exists and False if it doesn't. </p>
  
  <p>I tried <code>a.size:</code>, but if the array doesn't exist yet, it gives an error message, which I want to avoid.</p>
  
  <p>The situation demanding this happened in a loop, if you are wondering.</p>