From 259c10db10e5ead9f48da007cf30d28af1c9b9a9 Mon Sep 17 00:00:00 2001
From: Charles Tapley Hoyt <cthoyt@gmail.com>
Date: Sun, 26 Mar 2023 21:03:18 +0200
Subject: [PATCH] Revert optionals

---
 rdflib/plugins/sparql/processor.py | 16 ++++++++--------
 rdflib/plugins/sparql/update.py    |  2 +-
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/rdflib/plugins/sparql/processor.py b/rdflib/plugins/sparql/processor.py
index f10f372bc..68f5ee545 100644
--- a/rdflib/plugins/sparql/processor.py
+++ b/rdflib/plugins/sparql/processor.py
@@ -20,7 +20,7 @@
 
 def prepareQuery(
     queryString: str,
-    initNs: Optional[Mapping[str, Any]] = None,
+    initNs: Optional[Mapping[str, Any]] = {},
     base: Optional[str] = None,
 ) -> Query:
     """
@@ -35,7 +35,7 @@ def prepareQuery(
 
 def prepareUpdate(
     updateString: str,
-    initNs: Optional[Mapping[str, Any]] = None,
+    initNs: Optional[Mapping[str, Any]] = {},
     base: Optional[str] = None,
 ) -> Update:
     """
@@ -51,8 +51,8 @@ def prepareUpdate(
 def processUpdate(
     graph: Graph,
     updateString: str,
-    initBindings: Optional[Mapping[str, Identifier]] = None,
-    initNs: Optional[Mapping[str, Any]] = None,
+    initBindings: Optional[Mapping[str, Identifier]] = {},
+    initNs: Optional[Mapping[str, Any]] = {},
     base: Optional[str] = None,
 ) -> None:
     """
@@ -81,8 +81,8 @@ def __init__(self, graph):
     def update(
         self,
         strOrQuery: Union[str, Update],
-        initBindings: Optional[Mapping[str, Identifier]] = None,
-        initNs: Optional[Mapping[str, Any]] = None,
+        initBindings: Optional[Mapping[str, Identifier]] = {},
+        initNs: Optional[Mapping[str, Any]] = {},
     ) -> None:
         """
         .. caution::
@@ -116,8 +116,8 @@ def __init__(self, graph):
     def query(  # type: ignore[override]
         self,
         strOrQuery: Union[str, Query],
-        initBindings: Optional[Mapping[str, Identifier]] = None,
-        initNs: Optional[Mapping[str, Any]] = None,
+        initBindings: Optional[Mapping[str, Identifier]] = {},
+        initNs: Optional[Mapping[str, Any]] = {},
         base: Optional[str] = None,
         DEBUG: bool = False,
     ) -> Mapping[str, Any]:
diff --git a/rdflib/plugins/sparql/update.py b/rdflib/plugins/sparql/update.py
index 5ce86f393..5de59836a 100644
--- a/rdflib/plugins/sparql/update.py
+++ b/rdflib/plugins/sparql/update.py
@@ -282,7 +282,7 @@ def evalCopy(ctx: QueryContext, u: CompValue) -> None:
 def evalUpdate(
     graph: Graph,
     update: Update,
-    initBindings: Optional[Mapping[str, Identifier]] = None,
+    initBindings: Optional[Mapping[str, Identifier]] = {},
 ) -> None:
     """