diff --git a/src/csv.rs b/src/csv.rs
index 601741c..98aec41 100644
--- a/src/csv.rs
+++ b/src/csv.rs
@@ -252,7 +252,10 @@ fn run(start: Instant, logger: &slog::Logger) -> Result<usize, String> {
 
         if trade.ticker != t!(btc-usd) { continue }
 
-        if trade.time >= next_hour { // finalize last hour, and prepare for this hour
+        if trade.time >= next_hour { 
+            // `trade` is past the last hour bucket, so finalize/write last
+            // hour results, and reset state for this hour
+
             if n_bmex == 0 || n_gdax == 0 {
                 wtr.write_record(&[
                     &format!("{}", cur_hour), 
@@ -334,7 +337,7 @@ fn run(start: Instant, logger: &slog::Logger) -> Result<usize, String> {
         }
     }
 
-    // intentionally skipping the partial hour here 
+    // intentionally skipping handling the partial hour here 
     
     info!(logger, "finished parsing CSV/calculating query. closing output file");
     drop(wtr);
diff --git a/src/windows.rs b/src/windows.rs
new file mode 100644
index 0000000..5061c59
--- /dev/null
+++ b/src/windows.rs
@@ -0,0 +1 @@
+use std::collections::VecDeque;