Comment fix.

"None OR whatever" not "None OF whatever"

csppfetch/__init__.py

@@ -779,7 +779,7 @@ class Downloader:
           If False, if the desired files are not already present, it's a failure
         :param download_stats: Optional DownloadStatistics object to collect download
           statistics
-        :type download_stats: None of csppfetch.DownloadStatistics
+        :type download_stats: None or csppfetch.DownloadStatistics
 
         """
         base_urls = self.get_base_urls()
@@ -848,7 +848,7 @@ class Downloader:
 
         :param download_stats: Optional DownloadStatistics object to collect
             download statistics
-        :type download_stats: None of csppfetch.DownloadStatistics
+        :type download_stats: None or csppfetch.DownloadStatistics
 
         **timeout**, **retries**, and **retry_wait** are overriddeen by environment
         variables ``package_env_id+TIMEOUT/RETRIES/RETRY_WAIT``
@@ -881,7 +881,7 @@ class Downloader:
 
         :param download_stats: Optional DownloadStatistics object to collect
             download statistics
-        :type download_stats: None of csppfetch.DownloadStatistics
+        :type download_stats: None or csppfetch.DownloadStatistics
         """
         if end_time is not None and start_time is not None:
             time = self._nearest_preceeding_time(end_time)