Update code example to Python 3.9 syntax

Author: YuriiMotov

docs/advanced/advanced-relationships/self-referential.md

@@ -16,7 +16,7 @@ To allow more fine-grained control over it, the `Relationship` constructor allow
 
 Since SQLAlchemy relationships provide the [`remote_side`](https://docs.sqlalchemy.org/en/20/orm/relationship_api.html#sqlalchemy.orm.relationship.params.remote_side){.external-link target=_blank} parameter for just such an occasion, we can leverage that directly to construct the self-referential pattern with minimal code.
 
-{* ./docs_src/advanced/self_referential/tutorial001.py ln[6:18] hl[16] *}
+{* ./docs_src/advanced/self_referential/tutorial001_py39.py ln[6:18] hl[16] *}
 
 Using the `sa_relationship_kwargs` parameter, we pass the keyword argument `remote_side='Villain.id'` to the underlying relationship property.
 
@@ -46,17 +46,17 @@ Finally, as with regular (i.e. non-self-referential) foreign key relationships,
 
 Now let's see how we can create villains with a boss:
 
-{* ./docs_src/advanced/self_referential/tutorial001.py ln[31:50] hl[34:35] *}
+{* ./docs_src/advanced/self_referential/tutorial001_py39.py ln[31:50] hl[34:35] *}
 
 Just as with regular relationships, we can simply pass our boss villain as an argument to the constructor using `boss=thinnus`.
 
 If we later learn that a villain actually had a secret boss after we've already created him, we can just as easily assign that boss retroactively:
 
-{* ./docs_src/advanced/self_referential/tutorial001.py ln[31:32,52:56] hl[52] *}
+{* ./docs_src/advanced/self_referential/tutorial001_py39.py ln[31:32,52:56] hl[52] *}
 
 And if we want to add minions to a boss afterward, it's as easy as adding items to a Python list (because that's all it is 🤓):
 
-{* ./docs_src/advanced/self_referential/tutorial001.py ln[31:32,58:69] hl[61] *}
+{* ./docs_src/advanced/self_referential/tutorial001_py39.py ln[31:32,58:69] hl[61] *}
 
 Since our relationships work both ways, we don't even need to add all our `clone_bot_`s to the session individually. Instead, we can simply add `ultra_bot` again and commit the changes. We do need to refresh them individually, though, if we want to access their updated attributes.
 

…advanced/self_referential/tutorial001.py …ced/self_referential/tutorial001_py39.pydocs_src/advanced/self_referential/tutorial001.py renamed to docs_src/advanced/self_referential/tutorial001_py39.py docs_src/advanced/self_referential/tutorial001.py renamed to docs_src/advanced/self_referential/tutorial001_py39.py

@@ -1,4 +1,4 @@
-from typing import List, Optional
+from typing import Optional
 
 from sqlmodel import Field, Relationship, Session, SQLModel, create_engine
 
@@ -15,7 +15,7 @@ class Villain(SQLModel, table=True):
         back_populates="minions",
         sa_relationship_kwargs={"remote_side": "Villain.id"},
     )
-    minions: List["Villain"] = Relationship(back_populates="boss")
+    minions: list["Villain"] = Relationship(back_populates="boss")
 
 
 sqlite_file_name = "database.db"

tests/test_advanced/test_self_referential/test_tutorial001.py

@@ -81,7 +81,7 @@
 
 
 def test_tutorial(clear_sqlmodel):
-    from docs_src.advanced.self_referential import tutorial001 as mod
+    from docs_src.advanced.self_referential import tutorial001_py39 as mod
 
     mod.sqlite_url = "sqlite://"
     mod.engine = create_engine(mod.sqlite_url)