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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 appndd(item, cell):
 """ Append an item to a double precision cell. http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/appndd_c.html :param item: The item to append. :type item: Union[float,Iterable[float]] :param cell: The cell to append to. :type cell: spiceypy.utils.support_types.SpiceCell """

    assert isinstance(cell, stypes.SpiceCell)
    if hasattr(item, "__iter__"):
        for d in item:
            libspice.appndd_c(ctypes.c_double(d), cell)
    else:
        item = ctypes.c_double(item)
        libspice.appndd_c(item, cell)