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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 get_active_modifiers(self):
 """ Get a list of active keys. Uses XQueryKeymap. :return: list of charcodemap_t instances """

        keys = ctypes.pointer(charcodemap_t())
        nkeys = ctypes.c_int(0)

        _libxdo.xdo_get_active_modifiers(
            self._xdo, ctypes.byref(keys), ctypes.byref(nkeys))
        return [keys[i] for i in range(nkeys.value)]