--- a/configmix/config.py	Wed Nov 10 02:38:38 2021 +0100
+++ b/configmix/config.py	Wed Nov 10 02:43:23 2021 +0100
@@ -208,6 +208,17 @@
                 return default
 
     def getfirstvarl_s(self, *paths, **kwds):
+        """A variant of :meth:`~.getfirstvarl` that does variable
+        interpolation.
+
+        `paths` and `kwds` are interpreted as in :meth:`.getfirstvarl`.
+        But variables will be interpolated
+        recursively within the variable values and filters are
+        applied.
+
+        For more details see chapter :ref:`variable-interpolation`.
+
+        """
         default = kwds.pop("default", _MARKER)
         for path in paths:
             if isinstance(path, (list, tuple)):