Fix linting errors.

Author: kishorenc

typesense/collection.py

@@ -17,4 +17,4 @@ def retrieve(self):
         return self.api_call.get(self._endpoint_path())
 
     def delete(self):
-        return self.api_call.delete(self._endpoint_path())
+        return self.api_call.delete(self._endpoint_path())

typesense/collections.py

@@ -11,7 +11,7 @@ def __init__(self, config):
         self.collections = {}
 
     def __getitem__(self, collection_name):
-        if not collection_name in self.collections:
+        if collection_name not in self.collections:
             self.collections[collection_name] = Collection(self.config, collection_name)
 
         return self.collections.get(collection_name)

typesense/documents.py

@@ -12,7 +12,7 @@ def __init__(self, config, collection_name):
         self.documents = {}
 
     def __getitem__(self, document_id):
-        if not document_id in self.documents:
+        if document_id not in self.documents:
             self.documents[document_id] = Document(self.config, self.collection_name, document_id)
 
         return self.documents[document_id]