add abstract get_signature() to sqlalchemy.AuthSrc(), itertools.ltuple() and rtuple() and UserSigner.sign_object()

pyproject.toml

@@ -4,13 +4,15 @@ authors = [
     { name = "Sakuragasaki46" }
 ]
 dynamic = [ "version" ]
+requires-python = ">=3.10"
+license = "Apache-2.0"
+readme = "README.md"
+
 dependencies = [
     "itsdangerous",
     "toml"
 ]
-requires-python = ">=3.10"
-license = "Apache-2.0"
-readme = "README.md"
+# - further devdependencies below - #
 
 # - publishing -
 classifiers = [
@@ -28,6 +30,7 @@ classifiers = [
 Repository = "https://github.com/sakuragasaki46/suou"
 
 [project.optional-dependencies]
+# the below are all dev dependencies (and probably already installed)
 sqlalchemy = [
     "SQLAlchemy>=2.0.0"
 ]