How to restrict access to users?

Is it possible to restrict the access of a user to some of the cells of a given Notebook that I have in my JupyterHub? For example, I want this user to execute cells 1,2,3 but not 4, 5, 6. Or depending the requirement of the user execute different ones. Or is it just possible to determine which Notebooks can a user access, as once the Notebook is accessed it must be accessed fully?