Fix incorrect type of obj about previous frontier places

script_mac.py

@@ -25,10 +25,12 @@ class ErrorRep(object):
 
     def display(self, mess):
         self.error = True
-        LOGGER.debug(">> Context: {}; {}".format(self.context, mess))
+        LOGGER.error(">> Context: {}; {}".format(self.context, mess))
+        exit()
 
     def display_info(self, mess):
-        LOGGER.debug("-- Context: {}; {}".format(self.context, mess))
+        LOGGER.error("-- Context: {}; {}".format(self.context, mess))
+        exit()
 
     def set_context(self, cont):
         self.context = cont
@@ -113,20 +115,26 @@ def main2(chart_file, cam_file, cam_step_file, cam_complete_file, cam_strong_fil
                      steps, final_prop, start_prop, inv_prop)
 
         # Add theese frontier places to set of previous ones
-        previous_frontier_places.update(frontier_places)
+        # (tuple is hashable)
+        previous_frontier_places.add(tuple(frontier_places))
         LOGGER.debug("Prev frontier places: " + \
                      str(previous_frontier_places))
 
         # Compute the formula of the next start_property
         start_prop = make_logical_formula(previous_frontier_places,
                                           start_prop)
-        LOGGER.debug("Next start_prop formula: " + str(start_prop))
+        steps = min_steps
+        LOGGER.debug(
+            "Next start_prop formula: {} in {} steps".format(start_prop, steps)
+        )
 
 
 def find_mac(mcla,
              cam_file, cam_step_file, cam_complete_file,
              steps, final_prop, start_prop, inv_prop):
-
+    """
+    list, min step
+    """
     # Build query
     query = MCLSimpleQuery(start_prop, inv_prop, final_prop)