title: How to get variable unique identification number or string
body: <p>Using </p>
  
  <pre><code>a=7
  print hex(id(a))
  </code></pre>
  
  <p>getting back:</p>
  
  <pre><code>0x7f866b425e58
  </code></pre>
  
  <p>Intending to use this output (converted to string) as an identification number for each class object declared I need to make sure it would stay the same while the program is running. I also need to know if a second character is always 'x' (on mac, win and linux). If I am making a bad choice choosing <code>hex(id))</code> please let me know what would be a better option. </p>