Some documentation:
- https://cplusplus.com/reference/
- https://en.cppreference.com/w/cpp/container
- https://en.cppreference.com/w/cpp/iterator
- https://docs.microsoft.com/en-us/cpp/standard-library/cpp-standard-library-reference?view=msvc-170
- https://stackoverflow.com/questions/18385418/c-meaning-of-a-statement-combining-typedef-and-typename
- https://stackoverflow.com/questions/121162/what-does-the-explicit-keyword-mean