src/cpl_query/_extension/iterable.py

@@ -5,6 +5,7 @@ from cpl_query.extension.ordered_iterable_abc import OrderedIterableABC
 from .._query.all_query import all_query
 from .._query.any_query import any_query
 from .._query.avg_query import avg_query
+from .._query.contains_query import contains_query
 from .._query.first_query import first_or_default_query, first_query
 from .._query.for_each_query import for_each_query
 from .._query.order_by import order_by_query, order_by_descending_query
@@ -27,6 +28,9 @@ class Iterable(IterableABC):
     def average(self, t: type, func: Callable) -> Union[int, float, complex]:
         return avg_query(self, t, func)
 
+    def contains(self, value: object) -> bool:
+        return contains_query(self, value)
+
     def first(self) -> any:
         return first_query(self)
 

src/cpl_query/_query/contains_query.py

@@ -0,0 +1,5 @@
+from cpl_query.extension.iterable_abc import IterableABC
+
+
+def contains_query(_list: IterableABC, value: object) -> bool:
+    return value in _list

src/cpl_query/extension/iterable_abc.py

@@ -17,6 +17,9 @@ class IterableABC(ABC, list):
     @abstractmethod
     def average(self, t: type, func: Callable) -> Union[int, float, complex]: pass
 
+    @abstractmethod
+    def contains(self, value: object) -> bool: pass
+
     @abstractmethod
     def first(self) -> any: pass
 

src/cpl_query/tests/query_test.py

@@ -79,6 +79,10 @@ class QueryTest(unittest.TestCase):
         self.assertRaises(InvalidTypeException, invalid)
         self.assertRaises(WrongTypeException, wrong)
 
+    def test_contains(self):
+        self.assertTrue(self._tests.contains(self._t_user))
+        self.assertFalse(self._tests.contains(User("Test", None)))
+
     def test_first(self):
         results = []
         for user in self._tests: