Making get_last_before to return timestamp and data.

1 files changed, 6 insertions, 8 deletions

diff --git a/src/argaze/DataStructures.py b/src/argaze/DataStructures.py
index 2a8aed1..08bcac9 100644
--- a/src/argaze/DataStructures.py
+++ b/src/argaze/DataStructures.py
@@ -72,11 +72,7 @@ class TimeStampedBuffer(collections.OrderedDict):
         """Pop all item until a given timestamped value and return the last poped item."""
 
         # get last timestamp before given timestamp
-        earliest_ts = self.get_last_before(ts)
-
-        # when no timestamped have been found
-        if earliest_ts == None:
-            raise KeyError
+        earliest_ts, earliest_value = self.get_last_before(ts)
 
         popep_ts, poped_value = self.pop_first()
 
@@ -95,7 +91,7 @@ class TimeStampedBuffer(collections.OrderedDict):
 
         return self.popitem(last=True)
 
-    def get_last_before(self, ts) -> Tuple[TimeStampType, DataType] | None:
+    def get_last_before(self, ts) -> Tuple[TimeStampType, DataType]:
         """Retreive last item timestamp before a given timestamp value."""
 
         ts_list = list(self.keys())
@@ -103,11 +99,13 @@ class TimeStampedBuffer(collections.OrderedDict):
 
         if last_before_index >= 0:
 
-            return ts_list[last_before_index]
+            last_before_ts = ts_list[last_before_index]
+            
+            return last_before_ts, self[last_before_ts]
             
         else:
             
-            return None
+            raise KeyError(f'No data stored before {ts} timestamp.')
 
     def export_as_json(self, filepath):
         """Write buffer content into a json file."""