diff --git a/path.py b/path.py
index b32e9d3..0980ebd 100644
--- a/path.py
+++ b/path.py
@@ -15,7 +15,7 @@ def astar(graph, start, goal, cost = euclidian_distance, heuristic = euclidian_d
     closed = set()
     m_heur = {}
     m_parent = {}
-    m_cost = {} # path costs
+    m_cost = {} # absolute path costs
 
     def path_from(node):
         def parents(node):
@@ -33,25 +33,26 @@ def astar(graph, start, goal, cost = euclidian_distance, heuristic = euclidian_d
         # sort opened nodes based on the heuristic and consider the first one
         current = sorted(opened, key=lambda n : m_heur.get( n, heuristic(n,goal) ) )[0]
         if current == goal:
+            # FIXME add backtrack validation
             return path_from(current)
 
         closed.add(current)
         opened.remove(current)
 
-        for node in graph[current]:
-            if node in closed:
+        for neighbor in graph[current]:
+            if neighbor in closed:
                 continue
 
-            elif node in opened:
-                next_cost = m_cost[current] + cost(current,node)
-                if next_cost < m_cost[node]:
-                    m_cost[node] = next_cost
-                    m_parent[node] = current
+            elif neighbor in opened:
+                next_cost = m_cost[current] + cost(current,neighbor)
+                if next_cost < m_cost[neighbor]:
+                    m_cost[neighbor] = next_cost
+                    m_parent[neighbor] = current
             else:
-                m_cost[node] = m_cost[current] + cost(current,node)
-                m_heur[node] = heuristic( node, goal )
-                m_parent[node] = current
-                opened.add(node)
+                m_cost[neighbor] = m_cost[current] + cost(current,neighbor)
+                m_heur[neighbor] = heuristic( neighbor, goal )
+                m_parent[neighbor] = current
+                opened.add(neighbor)
     return []