Simplify per Pablo's review

Author: StanFromIreland

Grammar/python.gram

@@ -1316,7 +1316,7 @@ invalid_parameters:
         RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "/ must be ahead of *") }
     | param_maybe_default+ '/' a='*' {
         RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "expected comma between / and *") }
-    | !(param_maybe_default | '*' | '/' | '**') a=disjunction b=expression_without_invalid {
+    | a=NAME b=NAME {
         RAISE_SYNTAX_ERROR_KNOWN_RANGE(a, b, "expected comma between parameters") }
 invalid_default:
     | a='=' &(')'|',') { RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "expected default value expression") }
@@ -1346,7 +1346,7 @@ invalid_lambda_parameters:
         RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "/ must be ahead of *") }
     | lambda_param_maybe_default+ '/' a='*' {
         RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "expected comma between / and *") }
-    | !(lambda_param_maybe_default | '*' | '/' | '**') a=disjunction b=expression_without_invalid {
+    | a=NAME b=NAME {
         RAISE_SYNTAX_ERROR_KNOWN_RANGE(a, b, "expected comma between parameters") }
 invalid_lambda_parameters_helper:
     | a=lambda_slash_with_default { _PyPegen_singleton_seq(p, a) }