Clean up comments, remove an unneeded macro

Author: michaelbautin

hnswlib/hnswalg.h

@@ -1147,9 +1147,9 @@ class HierarchicalNSW : public AlgorithmInterface<dist_t> {
                         filteredTopCandidates.pop();
                 }
 
-                auto newElement = mutuallyConnectNewElement(dataPoint, dataPointInternalId, filteredTopCandidates, level, true);
-                HNSWLIB_RETURN_IF_VALUE_NOT_OK(newElement);
-                currObj = HNSWLIB_EXTRACT_VALUE(newElement);
+                HNSWLIB_ASSIGN_OR_RETURN(
+                    auto curObj,
+                    mutuallyConnectNewElement(dataPoint, dataPointInternalId, filteredTopCandidates, level, true));
             }
         }
         HNSWLIB_RETURN_OK_STATUS;
@@ -1268,9 +1268,9 @@ class HierarchicalNSW : public AlgorithmInterface<dist_t> {
                         top_candidates.pop();
                 }
 
-                auto newElement = mutuallyConnectNewElement(data_point, cur_c, top_candidates, level, false);
-                HNSWLIB_RETURN_IF_VALUE_NOT_OK(newElement);
-                currObj = HNSWLIB_EXTRACT_VALUE(newElement);
+                HNSWLIB_ASSIGN_OR_RETURN(
+                    currObj,
+                    mutuallyConnectNewElement(data_point, cur_c, top_candidates, level, false));
             }
         } else {
             // Do nothing for the first element

hnswlib/hnswlib.h

@@ -131,29 +131,18 @@ static bool AVX512Capable() {
 namespace hnswlib {
 
 // hnswlib can be compiled in two modes: with and without exceptions.
-// In the mode without exceptions, we use Abseil-style Status and StatusOr
-// return values but without actually introducing an Abseil dependency.
-// By default, we assume the legacy mode of using exceptions.
-
-// The following macros are defined for functions that can throw exceptions
-// or return statuses:
-//
-// HNSWLIB_THROW_ERROR(message) -- throw an exception or return a sttatus
-//     with the given message
-// HNSWLIB_STATUS_TYPE -- return type for a function without a return value
-// HNSWLIB_STATUS_OR_TYPE(t) -- return type for a function with a return value
-// HNSWLIB_RETURN_OK_STATUS -- return an OK status or simply return.
+// In the mode without exceptions, we use Status / StatusOr from Abseil.
+// By default, we assume the mode of using exceptions for compatibility.
 
 #if !HNSWLIB_USE_ABSEIL
 
-#define HNSWLIB_THROW_ERROR(message) \
-    throw std::runtime_error(message);
 #define HNSWLIB_STATUS_TYPE void
 #define HNSWLIB_STATUS_OR_TYPE(t) t
+#define HNSWLIB_THROW_ERROR(message) throw std::runtime_error(message);
 #define HNSWLIB_RETURN_OK_STATUS return
+#define HNSWLIB_RETURN_IF_VALUE_NOT_OK(status_or_value) status_or_value
 #define HNSWLIB_EXTRACT_VALUE(status_or_value) (status_or_value)
 #define HNSWLIB_ASSIGN_OR_RETURN(lhs, expression) lhs = (expression)
-#define HNSWLIB_RETURN_IF_VALUE_NOT_OK(status_or_value) status_or_value
 #define HNSWLIB_ASSIGN_VALUE_OR_THROW_IN_TEST(identifier, expression) \
     auto identifier = (expression)