def stack_id(self, function_address):
        """
        Return a memory region ID for a function. If the default region ID exists in the region mapping, an integer
        will appended to the region name. In this way we can handle recursive function calls, or a function that
        appears more than once in the call frame.

        This also means that `stack_id()` should only be called when creating a new stack frame for a function. You are
        not supposed to call this function every time you want to map a function address to a stack ID.

        :param int function_address: Address of the function.
        :return: ID of the new memory region.
        :rtype: str
        """
        region_id = 'stack_0x%x' % function_address

        # deduplication
        region_ids = self._stack_region_map.region_ids
        if region_id not in region_ids:
            return region_id
        else:
            for i in range(0, 2000):
                new_region_id = region_id + '_%d' % i
                if new_region_id not in region_ids:
                    return new_region_id
            raise SimMemoryError('Cannot allocate region ID for function %#08x - recursion too deep' % function_address)
Return a memory region ID for a function. If the default region ID exists in the region mapping, an integer
        will appended to the region name. In this way we can handle recursive function calls, or a function that
        appears more than once in the call frame.

        This also means that `stack_id()` should only be called when creating a new stack frame for a function. You are
        not supposed to call this function every time you want to map a function address to a stack ID.

        :param int function_address: Address of the function.
        :return: ID of the new memory region.
        :rtype: str