docs: def synthesize(self, duration, freqs_in_hz=[440.]):
          """
          Synthesize one or more sine waves
  
          Args:
              duration (numpy.timdelta64): The duration of the sound to be
                  synthesized
              freqs_in_hz (list of float): Numbers representing the frequencies
                  in hz that should be synthesized
          """
          freqs = np.array(freqs_in_hz)
          scaling = 1 / len(freqs)
          sr = int(self.samplerate)
          cps = freqs / sr
          ts = (duration / Seconds(1)) * sr
          ranges = np.array([np.arange(0, ts * c, c) for c in cps])
          raw = (np.sin(ranges * (2 * np.pi)) * scaling).sum(axis=0)
          return AudioSamples(raw, self.samplerate)