title: addition between classes using radd method
body: <p>I have two different classes, and I want to define the addition of them only in one class, and define both <code>__add__</code> and <code>__radd__</code> for that class (in my example below, that's <code>ExampleClass2</code>. I DO NOT want to create an <code>__add__</code> method that works for <code>ExampleClass1</code> to add <code>ExampleClass2</code>.</p>
  <p>As it is right now it just ignores it. I also tried with raising error, but that didn't work either.</p>
  <pre><code>class ExampleClass1:
      def __init__(self, data):
          self.data = data
          
      def __add__(self, other):
          if isinstance(other, int):
              print('other was an int')
          
          
  class ExampleClass2:
      def __init__(self, data):
          self.data = data
          
      def __add__(self, other):
          if isinstance(other, ExampleClass1):
              print(&quot;it's working&quot;)
              
      __radd__ = __add__
      
  a = ExampleClass1('q')
  
  b = ExampleClass2('w')
  
  a+b
  </code></pre>