title: instance block accessing instance variable before object creation
body: <p>I have a doubt regarding instance block and constructors. I have learnt that the instance block is always executed before the constructor.</p>
  
  <p>However if I try to access an instance variable, or even try to use 'this', there is no kind of error.
  But then how can I access an instance variable, even before it's object is created.</p>