title: Call a function in a class from different class
body: <p>I am creating an add-on. I am stuck in calling a method of a class from different class.
  For example...</p>
  
  <pre><code>class A(bpy.types.Operator):
      def execute(self,context):
      #Code
  class B(bpy.types.Operator):
      def execute(self,context):
      #Code
      Go back to class A...
  </code></pre>
  
  <p>I don't know how to do this......</p>