-# This corpus is fixed, (it happens to be 50 messages from early in
-# the history of the notmuch mailing list), which allows for reliably
+# $1 is the corpus dir under corpora to add, using "default" if unset.
+#
+# The default corpus is based on about 50 messages from early in the
+# history of the notmuch mailing list, which allows for reliably