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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 make_frequency_series(vec):
 """Return a frequency series of the input vector. If the input is a frequency series it is returned, else if the input vector is a real time series it is fourier transformed and returned as a frequency series. Parameters vector : TimeSeries or FrequencySeries Returns ------- Frequency Series: FrequencySeries A frequency domain version of the input vector. """

    if isinstance(vec, FrequencySeries):
        return vec
    if isinstance(vec, TimeSeries):
        N = len(vec)
        n = N/2+1
        delta_f = 1.0 / N / vec.delta_t
        vectilde =  FrequencySeries(zeros(n, dtype=complex_same_precision_as(vec)),
                                    delta_f=delta_f, copy=False)
        fft(vec, vectilde)
        return vectilde
    else:
        raise TypeError("Can only convert a TimeSeries to a FrequencySeries")