Added toggle_hv_preferred and set_vrange methods

And test cases for them, too.  Huzzah!

pdbuddy/__init__.py

         """Toggles the GiveBack flag in the configuration buffer"""
         self.send_command("toggle_giveback")
 
+    def toggle_hv_preferred(self):
+        """Toggles the HV_Preferred flag in the configuration buffer"""
+        self.send_command("toggle_hv_preferred")
+
     def set_v(self, mv):
         """Sets the voltage of the configuration buffer, in millivolts"""
         out = self.send_command("set_v {}".format(mv))
         if len(out):
             raise ValueError(out[0])
 
+    def set_vrange(self, vmin, vmax):
+        """Sets the min and max voltage of the configuration buffer, in millivolts"""
+        # First, make sure we're sending numbers to the Sink in all valid cases
+        if vmin is None and vmax is None:
+            vmin = 0
+            vmax = 0
+        out = self.send_command("set_vrange {} {}".format(vmin, vmax))
+        # If that command gave any output, that indicates an error.  Raise an
+        # exception to make that clear.
+        if len(out):
+            raise ValueError(out[0])
+
     def set_i(self, ma):
         """Sets the current of the configuration buffer, in milliamperes"""
         out = self.send_command("set_i {}".format(ma))
         self.clear_flags()
         if sc.flags & SinkFlags.GIVEBACK:
             self.toggle_giveback()
+        if sc.flags & SinkFlags.HV_PREFERRED:
+            self.toggle_hv_preferred()
 
         # Set voltage
         self.set_v(sc.v)
+
+        # Set voltage range
+        self.set_vrange(sc.vmin, sc.vmax)
         
         # Set current
         self.set_i(sc.i)

test_pdbuddy/__init__.py

         self.obj_valid_gb = pdbuddy.SinkConfig(status=pdbuddy.SinkStatus.VALID,
                 flags=pdbuddy.SinkFlags.GIVEBACK, v=15000, vmin=None,
                 vmax=None, i=3000)
+        self.obj_range = pdbuddy.SinkConfig(status=pdbuddy.SinkStatus.VALID,
+                flags=pdbuddy.SinkFlags.HV_PREFERRED, v=13800, vmin=12000,
+                vmax=16000, i=2000)
 
         self.obj_huge_v = pdbuddy.SinkConfig(status=pdbuddy.SinkStatus.VALID,
                 flags=pdbuddy.SinkFlags.NONE, v=65536, vmin=None, vmax=None,
                 flags=pdbuddy.SinkFlags.NONE, v=-1, vmin=None, vmax=None,
                 i=1000)
 
+        self.obj_inv_range = pdbuddy.SinkConfig(status=pdbuddy.SinkStatus.VALID,
+                flags=pdbuddy.SinkFlags.HV_PREFERRED, v=13800, vmin=16000,
+                vmax=12000, i=2000)
+
         self.obj_huge_i = pdbuddy.SinkConfig(status=pdbuddy.SinkStatus.VALID,
                 flags=pdbuddy.SinkFlags.NONE, v=5000, vmin=None, vmax=None,
                 i=65536)
         self.pdbs.set_tmpcfg(self.obj_valid_gb)
         self.assertEqual(self.pdbs.get_tmpcfg(), self.obj_valid_gb)
 
+    def test_set_tmpcfg_range(self):
+        self.pdbs.set_tmpcfg(self.obj_range)
+        self.assertEqual(self.pdbs.get_tmpcfg(), self.obj_range)
+
     def test_set_tmpcfg_huge_v(self):
         with self.assertRaises(ValueError):
             self.pdbs.set_tmpcfg(self.obj_huge_v)
         with self.assertRaises(ValueError):
             self.pdbs.set_tmpcfg(self.obj_neg_v)
 
+    def test_set_tmpcfg_inv_range(self):
+        with self.assertRaises(ValueError):
+            self.pdbs.set_tmpcfg(self.obj_inv_range)
+
     def test_set_tmpcfg_huge_i(self):
         with self.assertRaises(ValueError):
             self.pdbs.set_tmpcfg(self.obj_huge_i)