base: fix flake8 complaints

xbstrap/base.py

@@ -94,7 +94,7 @@ def try_rmtree(path):
 
 def stat_mtime(path):
     try:
-        with open(path) as f:
+        with open(path) as _:
             stat = os.stat(path)
             return stat.st_mtime
     except FileNotFoundError:
@@ -816,8 +816,11 @@ def traverse_graph(*, roots, visit, key=None):
     seen = set()
     stack = []
 
+    def default_mapping(n):
+        return
+
     if key is None:
-        key = lambda n: n
+        key = default_mapping
 
     for n in roots:
         k = key(n)
@@ -2351,7 +2354,7 @@ def run_program(
                 )
             else:
                 if verbosity:
-                    _util.log_info(f"Sysroot is not bind mounted")
+                    _util.log_info("Sysroot is not bind mounted")
 
             with tempfile.NamedTemporaryFile("w+") as f:
                 json.dump(cbuild_json, f)
@@ -3564,12 +3567,12 @@ def _do_ordering(self):
                 item.reverse_edge_list.append(target_item)
 
         # Sort all edge lists to make the order deterministic.
-        def sort_items(l):
-            l.sort(key=PlanItem.get_ordering_key)
+        def sort_items(items):
+            items.sort(key=PlanItem.get_ordering_key)
             # Alternatively, shuffle the edge lists to randomize the order.
             # Note that sorting them first ensures that the order is deterministic.
             if self.ordering_prng:
-                self.ordering_prng.shuffle(l)
+                self.ordering_prng.shuffle(items)
 
         root_list = list(self._items.values())
         sort_items(root_list)