This is a very minor adjustment.

a + b is list-specific behavior, but we can accept a wider variety of
types in a more pythonic fashion if we avoid that behavior.

Typing it this way allows callers to use things like dict.keys() and
other iterables that are not their own discrete lists.

Including it just as a statement of practice if nothing else: It's nice
to use the least-specific type possible as function input and use the
most-specific type for returns.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Cleber Rosa <crosa@redhat.com>
---
 scripts/qapi/expr.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/scripts/qapi/expr.py b/scripts/qapi/expr.py
index 8ad82ca98864..883aa1781599 100644
--- a/scripts/qapi/expr.py
+++ b/scripts/qapi/expr.py
@@ -133,8 +133,8 @@ def check_defn_name_str(name: str, info: QAPISourceInfo, meta: str) -> None:
 def check_keys(value: _JSObject,
                info: QAPISourceInfo,
                source: str,
-               required: List[str],
-               optional: List[str]) -> None:
+               required: Iterable[str] = (),
+               optional: Iterable[str] = ()) -> None:
     """
     Ensures an object has a specific set of keys. [Const]
 
@@ -155,7 +155,7 @@ def pprint(elems: Iterable[str]) -> str:
             "%s misses key%s %s"
             % (source, 's' if len(missing) > 1 else '',
                pprint(missing)))
-    allowed = set(required + optional)
+    allowed = set(required) | set(optional)
     unknown = set(value) - allowed
     if unknown:
         raise QAPISemError(
-- 
2.26.2