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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 call(self, callsite_addr, addr, retn_target=None, stack_pointer=None):
 """ Push a stack frame into the call stack. This method is called when calling a function in CFG recovery. :param int callsite_addr: Address of the call site :param int addr: Address of the call target :param int or None retn_target: Address of the return target :param int stack_pointer: Value of the stack pointer :return: None """


        frame = CallStack(call_site_addr=callsite_addr, func_addr=addr, ret_addr=retn_target,
                          stack_ptr=stack_pointer)
        return self.push(frame)