new_contents: 
  import simuvex
  
  ######################################
  # Caller
  ######################################
  
  
  class Caller(simuvex.SimProcedure):
      """
      Caller stub. Creates a Ijk_Call exit to the specified function
      """
  
      def run(self, target_addr=None):
          self.call(target_addr, [ ], self.after_call)
  
      def after_call(self):
          pass
  
subject: Add a new SimProcedure stub Caller