Add type hint for create method (#377)

Add type hint to create method

Create is an important method. By adding type hinting the workflow is
improved a lot.

Co-authored-by: Christian.Wickboldt <[email protected]>

pylatex/base_classes/containers.py

@@ -5,9 +5,12 @@
 ..  :copyright: (c) 2014 by Jelte Fennema.
     :license: MIT, see License for more details.
 """
+from __future__ import annotations
 
 from collections import UserList
 from contextlib import contextmanager
+from typing import TypeVar
+from collections.abc import Generator
 
 from pylatex.utils import dumps_list
 
@@ -95,7 +98,7 @@ def dumps_packages(self):
         return super().dumps_packages()
 
     @contextmanager
-    def create(self, child):
+    def create(self, child: T) -> Generator[T, None, None]:
         """Add a LaTeX object to current container, context-manager style.
 
         Args
@@ -113,6 +116,9 @@ def create(self, child):
         self.append(child)
 
 
+T = TypeVar("T", bound=Container)
+
+
 class Environment(Container):
     r"""A base class for LaTeX environments.