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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 from_spectra(cls, *spectra, **kwargs):
 """Build a new `Spectrogram` from a list of spectra. Parameters *spectra any number of `~gwpy.frequencyseries.FrequencySeries` series dt : `float`, `~astropy.units.Quantity`, optional stride between given spectra Returns ------- Spectrogram a new `Spectrogram` from a vertical stacking of the spectra The new object takes the metadata from the first given `~gwpy.frequencyseries.FrequencySeries` if not given explicitly Notes ----- Each `~gwpy.frequencyseries.FrequencySeries` passed to this constructor must be the same length. """

        data = numpy.vstack([s.value for s in spectra])
        spec1 = list(spectra)[0]
        if not all(s.f0 == spec1.f0 for s in spectra):
            raise ValueError("Cannot stack spectra with different f0")
        if not all(s.df == spec1.df for s in spectra):
            raise ValueError("Cannot stack spectra with different df")
        kwargs.setdefault('name', spec1.name)
        kwargs.setdefault('channel', spec1.channel)
        kwargs.setdefault('epoch', spec1.epoch)
        kwargs.setdefault('f0', spec1.f0)
        kwargs.setdefault('df', spec1.df)
        kwargs.setdefault('unit', spec1.unit)
        if not ('dt' in kwargs or 'times' in kwargs):
            try:
                kwargs.setdefault('dt', spectra[1].epoch.gps - spec1.epoch.gps)
            except (AttributeError, IndexError):
                raise ValueError("Cannot determine dt (time-spacing) for "
                                 "Spectrogram from inputs")
        return Spectrogram(data, **kwargs)