Use DU in filename

scripts/pmt_rates.py

@@ -50,7 +50,8 @@ class PMTRates(kp.Module):
         self.du = self.require("du")
         self.interval = self.get("interval", default=10)
         self.plot_path = self.get("plot_path", default="plots")
-        self.filename = self.get("filename", default="pmt_rates.png")
+        self.filename = self.get("filename",
+                                 default=f"pmt_rates_{self.du}.png")
         self.lowest_rate = self.get("lowest_rate", default=5000)
         self.highest_rate = self.get("highest_rate", default=15000)
         self.max_x = 800