Only support a single leading underscore

Author: jparise

src/pep8ext_naming.py

@@ -540,7 +540,7 @@ def visit_module(self, node, parents: Sequence, ignored: NameSet):
             if not args or args[0] != name:
                 yield self.err(body, 'N808', name=name)
 
-            stripped_name = name.lstrip('_')
+            stripped_name = name.removeprefix('_')
             if not stripped_name[:1].isupper():
                 yield self.err(body, 'N808', name=name)
 

testsuite/N808.py

@@ -43,7 +43,10 @@
 Good = TypeVar("Good")
 
 #: Okay
-__Good = TypeVar("__Good")
+_Good = TypeVar("_Good")
+
+#: N808
+__NotGood = TypeVar("__NotGood")
 
 #: N808
 __NotGood__ = TypeVar("__NotGood__")