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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 fd_to_td(htilde, delta_t=None, left_window=None, right_window=None, left_beta=8, right_beta=8):
 """Converts a FD waveform to TD. A window can optionally be applied using ``fd_taper`` to the left or right side of the waveform before being converted to the time domain. Parameters htilde : FrequencySeries The waveform to convert. delta_t : float, optional Make the returned time series have the given ``delta_t``. left_window : tuple of float, optional A tuple giving the start and end frequency of the FD taper to apply on the left side. If None, no taper will be applied on the left. right_window : tuple of float, optional A tuple giving the start and end frequency of the FD taper to apply on the right side. If None, no taper will be applied on the right. left_beta : int, optional The beta parameter to use for the left taper. See ``fd_taper`` for details. Default is 8. right_beta : int, optional The beta parameter to use for the right taper. Default is 8. Returns ------- TimeSeries The time-series representation of ``htilde``. """

    if left_window is not None:
        start, end = left_window
        htilde = fd_taper(htilde, start, end, side='left', beta=left_beta)
    if right_window is not None:
        start, end = right_window
        htilde = fd_taper(htilde, start, end, side='right', beta=right_beta)
    return htilde.to_timeseries(delta_t=delta_t)