Apply suggestions from code review

Co-authored-by: Brett Cannon <[email protected]>

Author: serhiy-storchaka

Lib/importlib/_bootstrap.py

@@ -27,10 +27,10 @@ def _object_name(obj):
         return type(obj).__qualname__
 
 def _normalize(name):
-    """ Normalize 'name' in NKFC form """
+    """Normalize 'name' to NKFC form."""
     global _unicodedata_normalize
     if _unicodedata_normalize is None:
-        from unicodedata import _normalize
+        from unicodedata import normalize as _unicodedata_normalize
     return _unicodedata_normalize('NFKC', name)
 
 # Bootstrap-related code ######################################################
@@ -43,7 +43,7 @@ def _normalize(name):
 # Import done by _install_external_importers()
 _bootstrap_external = None
 
-# Import done as needed by _normalize
+# Import done lazily as needed by _normalize as unicodedata is not built-in.
 _unicodedata_normalize = None
 
 def _wrap(new, old):

Lib/importlib/_bootstrap_external.py

@@ -1591,8 +1591,8 @@ def __init__(self, path, *loader_details):
         else:
             self.path = _path_abspath(path)
         self._path_mtime = -1
-        self._path_cache = dict()
-        self._relaxed_path_cache = dict()
+        self._path_cache = {}
+        self._relaxed_path_cache = {}
         self._cache_is_normalized = False
 
     def invalidate_caches(self):
@@ -1686,7 +1686,7 @@ def _fill_cache(self):
             # so it's done once instead of for every import. This is safe as
             # the specified suffixes to check against are always specified in a
             # case-sensitive manner.
-            lower_suffix_contents = dict()
+            lower_suffix_contents = {}
             for item in contents:
                 name, dot, suffix = item.partition('.')
                 if dot:
@@ -1701,9 +1701,7 @@ def _fill_cache(self):
         self._cache_is_normalized = False
 
     def _normalize_cache(self):
-        """
-        Normalize all entries in the caches to NFKC.
-        """
+        """Normalize all entries in the caches to NFKC."""
         from unicodedata import normalize
 
         self._path_cache = { normalize('NFKC', p): p for p in self._path_cache }