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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 wnvald(insize, n, window):
 """ Form a valid double precision window from the contents of a window array. http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/wnvald_c.html :param insize: Size of window. :type insize: int :param n: Original number of endpoints. :type n: int :param window: Input window. :type window: spiceypy.utils.support_types.SpiceCell :return: The union of the intervals in the input cell. :rtype: spiceypy.utils.support_types.SpiceCell """

    assert isinstance(window, stypes.SpiceCell)
    assert window.dtype == 1
    insize = ctypes.c_int(insize)
    n = ctypes.c_int(n)
    libspice.wnvald_c(insize, n, ctypes.byref(window))
    return window