diff --git a/modules/10_cpp14/src/generic_lambdas.cpp b/modules/10_cpp14/src/generic_lambdas.cpp
index 9870d74..3df0193 100644
--- a/modules/10_cpp14/src/generic_lambdas.cpp
+++ b/modules/10_cpp14/src/generic_lambdas.cpp
@@ -1,16 +1,21 @@
 #include "generic_lambdas.hpp"
 
+#include <algorithm>
+
 namespace cpp14 {
 
 auto apply_twice(const std::vector<int>& values) -> std::vector<int> {
-    (void)values;
-    return {};
+    auto r = std::vector<int>(values.size());
+    std::ranges::transform(values, r.begin(), [](auto x) { return x * 2; });
+    return r;
 }
 
 auto concat_any(const std::vector<std::string>& a, const std::vector<std::string>& b)
     -> std::vector<std::string> {
-    (void)a; (void)b;
-    return {};
+    auto r = std::vector<std::string>(a.size() + b.size());
+    std::ranges::transform(a, r.begin(), [](auto x) { return x; });
+    std::ranges::transform(b, r.begin() + a.size(), [](auto x) { return x; });
+    return r;
 }
 
 }  // namespace cpp14