$ valgrind ./list-leak
[68.5, 72.0, 65.3]
==2303169== HEAP SUMMARY:
==2303169==     in use at exit: 24 bytes in 2 blocks
==2303169==   total heap usage: 4 allocs, 2 frees, 1,072 bytes allocated
==2303169== LEAK SUMMARY:
==2303169==    definitely lost: 24 bytes in 2 blocks