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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _add_return_site(self, return_site):
 """ Registers a basic block as a site for control flow to return from this function. :param CodeNode return_site: The block node that ends with a return. """

        self._register_nodes(True, return_site)

        self._ret_sites.add(return_site)
        # A return site must be an endpoint of the function - you cannot continue execution of the current function
        # after returning
        self._add_endpoint(return_site, 'return')