diff --git a/spcd/util.py b/spcd/util.py
index 2f8a7ab..73a5309 100644
--- a/spcd/util.py
+++ b/spcd/util.py
@@ -12,7 +12,15 @@ from spcd.shell import env
 
 
 def add_url_path(url: str, extra_path: str) -> str:
-    """Append an extra segment to an existing URL."""
+    """Append an extra segment to an existing URL.
+
+    :param url: base URL
+    :type url: str
+    :param extra_path: path to append
+    :type extra_path: str
+    :return: new URL
+    :rtype: str
+    """
     parts = urlparse(url)
     parts = parts._replace(path=str(Path(parts.path) / extra_path))
     return urlunparse(parts)