diff --git a/CMakeLists.txt b/CMakeLists.txt
index bef1c6b7..ebe53013 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -219,5 +219,3 @@ add_custom_command(TARGET regression_tests PRE_BUILD
                    ${RTESTS_DATA}
                    regression_test_data/old_data/.)
 add_custom_command(TARGET regression_tests POST_BUILD COMMAND regression_tests COMMENT "Running regression tests")
-
-
diff --git a/src/sydevs/core/arraynd.h b/src/sydevs/core/arraynd.h
index 3703c23c..b351295b 100644
--- a/src/sydevs/core/arraynd.h
+++ b/src/sydevs/core/arraynd.h
@@ -1164,20 +1164,30 @@ std::ostream& operator<<(std::ostream& os, const arraynd<T, ndims>& rhs)
     os << "{";
     while (idim >= 0) {
         if (indices[idim] < rhs.dims()[idim]) {
+            // The index is not beyond the last element on the current axis.
+            // Continue outputting the current sub-array.
             if (indices[idim] > 0) {
+                // This is not the first element on the current axis.
+                // Output a delimiter.
                 os << ", ";
             }
             if (idim == ndims - 1) {
+                // The current axis is the last one.
+                // Output the current element and advance the index.
                 os << rhs.data()[offset];
                 ++indices[idim];
                 offset += rhs.strides()[idim];
             }
             else {
+                // The current axis is not the last one.
+                // Start outputting a new sub-array.
                 ++idim;
                 os << "{";
             }
         }
         else {
+            // The index is beyond the last element on the current axis.
+            // Finish outputting the current sub-array.
             indices[idim] = 0;
             offset -= rhs.dims()[idim]*rhs.strides()[idim];
             --idim;
diff --git a/src/sydevs/systems/simulation.h b/src/sydevs/systems/simulation.h
index f42077ea..9a478837 100644
--- a/src/sydevs/systems/simulation.h
+++ b/src/sydevs/systems/simulation.h
@@ -406,17 +406,21 @@ inline void simulation<Node>::advance_time()
     if (!finishing_) {
         auto planned_dt = t_queue_.imminent_duration();
         if (planned_dt.finite() || !can_end_early_) {
+            // The event time must advance.
             event_time().advance(planned_dt, end_t_);
             if (planned_dt > 0_s) {
+                // The simulated time just advanced.
                 external_context_.time_printed() = false;
                 t_queue_.advance_time(event_time().t());
                 t_cache_.advance_time(event_time().t());
             }
             if (event_time().t() >= end_t_) {
+                // The end time has been reached.
                 finishing_ = true;
             }
         }
         else {
+            // The simulation must finish at the current event time.
             finishing_ = true;
         }
     }