title: Two ways to declare instance variables in Python?
body: <p>Is there any difference in functionality and what happens behind the scenes between</p>
  
  <pre><code>class Class:
      def __init__(self, var1):
          self.var1 = var1
  </code></pre>
  
  <p>and</p>
  
  <pre><code>class Class:
      var1 = ""
      def __init__(self, var1):
          self.var1 = var1
  </code></pre>
  
  <p>in Python?</p>