How does polyphemus prevent odysseus and his men from leaving his cave?

elon musk, ceo of spacex, a startup space company is planning to head to mars by 2023. nasa is planning to go to mars at around 2025. both are just for a basic colony.

  this riddles' answer is library.

  the "leaves" are a reference to the books' pages that the library contains; the branches are a network of libraries that connect multiple libraries' collections, resources, and items in a system of a common database, integrating them; the branches' organization are a useful management tool for coordinating the multiple collections many libraries have.