code: def _write_to_graph(self):
          
          traces = []
          for byte_code, trace_data in self.coverage.items():
              traces += [list(trace_data.keys()), list(trace_data.values()), "r--"]
  
          plt.plot(*traces)
          plt.axis([0, self.end - self.begin, 0, 100])
          plt.xlabel("Duration (seconds)")
          plt.ylabel("Coverage (percentage)")
  
          plt.savefig("{}.png".format(self.name))
docs: Write the coverage results to a graph