Issue #17331: Use isidentifier() instead of isalnum() to check for valid identifiers.

Lib/collections/__init__.py

@@ -323,24 +323,19 @@ def namedtuple(typename, field_names, verbose=False, rename=False):
     if rename:
         seen = set()
         for index, name in enumerate(field_names):
-            if (not all(c.isalnum() or c=='_' for c in name)
+            if (not name.isidentifier()
                 or _iskeyword(name)
-                or not name
-                or name[0].isdigit()
                 or name.startswith('_')
                 or name in seen):
                 field_names[index] = '_%d' % index
             seen.add(name)
     for name in [typename] + field_names:
-        if not all(c.isalnum() or c=='_' for c in name):
-            raise ValueError('Type names and field names can only contain '
-                             'alphanumeric characters and underscores: %r' % name)
+        if not name.isidentifier():
+            raise ValueError('Type names and field names must be valid '
+                             'identifiers: %r' % name)
         if _iskeyword(name):
             raise ValueError('Type names and field names cannot be a '
                              'keyword: %r' % name)
-        if name[0].isdigit():
-            raise ValueError('Type names and field names cannot start with '
-                             'a number: %r' % name)
     seen = set()
     for name in field_names:
         if name.startswith('_') and not rename: