Instead of pass (an implicit return none), use raise NotImplementedError
to mark a function as abstract -- one that doesn't return. This allows
us to correctly type the stub.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 scripts/qapi/schema.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py
index 0201b42095..a53631e660 100644
--- a/scripts/qapi/schema.py
+++ b/scripts/qapi/schema.py
@@ -176,8 +176,8 @@ def visit(self, visitor):
 class QAPISchemaType(QAPISchemaEntity):
     # Return the C type for common use.
     # For the types we commonly box, this is a pointer type.
-    def c_type(self):
-        pass
+    def c_type(self) -> str:
+        raise NotImplementedError()
 
     # Return the C type to be used in a parameter list.
     def c_param_type(self):
@@ -187,8 +187,8 @@ def c_param_type(self):
     def c_unboxed_type(self):
         return self.c_type()
 
-    def json_type(self):
-        pass
+    def json_type(self) -> str:
+        raise NotImplementedError()
 
     def alternate_qtype(self):
         json2qtype = {
-- 
2.26.2