Merge pull request #4755 from dohvis/patch-1

Add return type on cookies.py
diff --git a/requests/cookies.py b/requests/cookies.py
index 50883a8..72e94be 100644
--- a/requests/cookies.py
+++ b/requests/cookies.py
@@ -511,6 +511,7 @@
     :param cookiejar: (optional) A cookiejar to add the cookies to.
     :param overwrite: (optional) If False, will not replace cookies
         already in the jar with new ones.
+    :rtype: CookieJar
     """
     if cookiejar is None:
         cookiejar = RequestsCookieJar()
@@ -529,6 +530,7 @@
 
     :param cookiejar: CookieJar object to add the cookies to.
     :param cookies: Dictionary or CookieJar object to be added.
+    :rtype: CookieJar
     """
     if not isinstance(cookiejar, cookielib.CookieJar):
         raise ValueError('You can only merge into CookieJar')