new_contents: import matplotlib.pyplot as plot
  
  class WaveformImageRenderer(object):
      def __init__(self, interpretations):
          self.durations   = self.get_durations(interpretations)
          self.frequencies = self.get_frequencies(interpretations)
  
      def get_durations(self, interpretations):
          durations = []
  
          for interpretation in interpretations:
              durations.append(interpretation[0])
  
          return durations
  
      def get_frequencies(self, interpretations):
          frequencies = []
  
          for interpretation in interpretations:
              frequencies.append(interpretation[1])
  
          return frequencies
  
      def draw(self):
          plot.plot(self.durations, self.frequencies, 'ro')
  
      def save(self, filename):
          plot.savefig(filename)
  
subject: create WIP waveform image renderer