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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 callback(cfunc):
 """ Turn a ctypes CFUNCTYPE instance into a value which can be passed into PyROOT """

    # Note:
    # ROOT wants a c_voidp whose addressof() == the call site of the target
    # function. This hackery is necessary to achieve that.
    return C.c_voidp.from_address(C.cast(cfunc, C.c_voidp).value)