Python.asdl: few modifications to compile it

grammar/Python.asdl

@@ -43,7 +43,7 @@ module Python
           | Assert(expr test, expr? msg)
 
           | Import(alias* names)
-          | ImportFrom(identifier? module, alias* names, int? level)
+          | ImportFrom(identifier? module, alias* names, int level)
 
           | Global(identifier* names)
           | Nonlocal(identifier* names)
@@ -72,9 +72,9 @@ module Python
          | YieldFrom(expr value)
          -- need sequences for compare to distinguish between
          -- x < 4 < 3 and (x < 4) < 3
-         | Compare(expr left, cmpop* ops, expr* comparators)
+         | Compare(expr left, cmpop ops, expr* comparators)
          | Call(expr func, expr* args, keyword* keywords)
-         | FormattedValue(expr value, int? conversion, expr? format_spec)
+         | FormattedValue(expr value, int conversion, expr? format_spec)
          | JoinedStr(expr* values)
          -- | Constant(constant value, string? kind)
          -- Our specific nodes that are used instead of Constant:
@@ -113,8 +113,8 @@ module Python
     excepthandler = ExceptHandler(expr? type, identifier? name, stmt* body)
                     attributes (int lineno, int col_offset, int? end_lineno, int? end_col_offset)
 
-    arguments = (arg* posonlyargs, arg* args, arg? vararg, arg* kwonlyargs,
-                 expr* kw_defaults, arg? kwarg, expr* defaults)
+    arguments = (arg* posonlyargs, arg* args, arg* vararg, arg* kwonlyargs,
+                 expr* kw_defaults, arg* kwarg, expr* defaults)
 
     arg = (identifier arg, expr? annotation, string? type_comment)
            attributes (int lineno, int col_offset, int? end_lineno, int? end_col_offset)
@@ -132,7 +132,8 @@ module Python
     match_case = (pattern pattern, expr? guard, stmt* body)
 
     pattern = MatchValue(expr value)
-            | MatchSingleton(constant value)
+            -- | MatchSingleton(constant value)
+            | MatchSingleton(expr value)
             | MatchSequence(pattern* patterns)
             | MatchMapping(expr* keys, pattern* patterns, identifier? rest)
             | MatchClass(expr cls, pattern* patterns, identifier* kwd_attrs, pattern* kwd_patterns)