Let's be explicit with asserts; there was a bug in histogram

caused by assert foo when foo was an int with valid valid 0.

1 files changed, 2 insertions, 2 deletions

diff --git a/persistent.py b/persistent.py
index 8832572..16f51c0 100644
--- a/persistent.py
+++ b/persistent.py
@@ -64,7 +64,7 @@ def was_file_written_today(filename: str) -> bool:
         return False
 
     mtime = file_utils.get_file_mtime_as_datetime(filename)
-    assert mtime
+    assert mtime is not None
     now = datetime.datetime.now()
     return mtime.month == now.month and mtime.day == now.day and mtime.year == now.year
 
@@ -81,7 +81,7 @@ def was_file_written_within_n_seconds(
         return False
 
     mtime = file_utils.get_file_mtime_as_datetime(filename)
-    assert mtime
+    assert mtime is not None
     now = datetime.datetime.now()
     return (now - mtime).total_seconds() <= limit_seconds