def wnexpd(left, right, window):
    """
    Expand each of the intervals of a double precision window.

    http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/wnexpd_c.html

    :param left: Amount subtracted from each left endpoint. 
    :type left: float
    :param right: Amount added to each right endpoint. 
    :type right: float
    :param window: Window to be expanded. 
    :type window: spiceypy.utils.support_types.SpiceCell
    :return: Expanded Window.
    :rtype: spiceypy.utils.support_types.SpiceCell
    """
    assert isinstance(window, stypes.SpiceCell)
    assert window.dtype == 1
    left = ctypes.c_double(left)
    right = ctypes.c_double(right)
    libspice.wnexpd_c(left, right, ctypes.byref(window))
    return window