<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def default_empty(shape, dtype):
 """Numpy's empty array can have random values in it. To prevent that, we define here a default emtpy array. This default empty is a numpy.zeros array, except that objects are set to None, and all ints to ID_NOT_SET. """

    default = numpy.zeros(shape, dtype=dtype)
    set_default_empty(default)
    return default