LLVM e.g. SmallVector: https://llvm.org/doxygen/SmallVector_8h_source.html

Folly e.g. https://github.com/facebook/folly/tree/master/folly/logging, https://github.com/facebook/folly/blob/master/folly/concurre..., https://github.com/facebook/folly/tree/master/folly/executor...