lesson_check: add missing docstring

diff --git a/bin/lesson_check.py b/bin/lesson_check.py
index 6aa1c2c9b03b2a4d3792762f86665f8d64f1a18e..62ab7324f18f797fefb47cb52b90a5500dd50c35 100755 (executable)
--- a/bin/lesson_check.py
+++ b/bin/lesson_check.py
@@ -473,6 +473,7 @@ class CheckEpisode(CheckBase):
                 self.check_metadata_fields(TEACHING_METADATA_FIELDS)
 
     def check_metadata_fields(self, expected):
+        """Check metadata fields."""
         for (name, type_) in expected:
             if name not in self.metadata:
                 self.reporter.add(self.filename,