Add types.py with QuerySetType implementation

README.md

@@ -695,6 +695,8 @@ class Payment(models.Model):
 
 **This is our selector:**
 
+For implementation of `QuerySetType`, check `types.py`.
+
 ```python
 from django.contrib.auth.models import User
 

types.py

@@ -0,0 +1,49 @@
+from typing import Generic, Iterator, Any, TypeVar, Optional, Dict, Tuple
+from collections import Iterable
+
+
+DjangoModel = TypeVar('DjangoModel')
+
+
+class QuerySetType(Generic[DjangoModel], extra=Iterable):
+    """
+    This type represents django.db.models.QuerySet interface.
+
+    Defined Types:
+        DjangoModel - model instance
+        QuerysetType[DjangoModel] - Queryset of DjangoModel instances
+        Iterator[DjangoModel] - Iterator of DjangoModel instances
+    """
+    def __iter__(self) -> Iterator[DjangoModel]: ...
+
+    def all(self) -> 'QuerySetType[DjangoModel]': ...
+
+    def order_by(self, *args: Any) -> 'QuerySetType[DjangoModel]': ...
+
+    def count(self) -> int: ...
+
+    def filter(self, **kwargs: Any) -> 'QuerySetType[DjangoModel]': ...
+
+    def exclude(self, **kwargs: Any) -> 'QuerySetType[DjangoModel]': ...
+
+    def get(self, **kwargs: Any) -> DjangoModel: ...
+
+    def annotate(self, **kwargs: Any) -> 'QuerySetType[DjangoModel]': ...
+
+    def first(self) -> Optional[DjangoModel]: ...
+
+    def update(self, **kwargs: Any) -> DjangoModel: ...
+
+    def delete(self, **kwargs: Any) -> Tuple[int, Dict[str, int]]: ...
+
+    def last(self) -> Optional[DjangoModel]: ...
+
+    def exists(self) -> bool: ...
+
+    def values(self, *args: Any) -> 'QuerySetType[DjangoModel]': ...
+
+    def values_list(self, *args: Any) -> 'QuerySetType[DjangoModel]': ...
+
+    def __getitem__(self, index: int) -> DjangoModel: ...
+
+    def __len__(self) -> int: ...