How can the currently logged-in user be accessed from any point in the code?

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This depends on the programming language and framework being used. In general, the currently logged-in user can be accessed through the session or authentication system.

For example, in a web application built with Django (a Python web framework), the currently logged-in user can be accessed through the request object:

def my_view(request):
    user = request.user
    # Code to do something with the user object

In a Ruby on Rails web application, the currently logged-in user can be accessed through the current_user helper method:

def my_action
  user = current_user
  # Code to do something with the user object
end

In a desktop application, the currently logged-in user may be accessed through the operating system's user management API.

Overall, the specific method for accessing the currently logged-in user will depend on the programming language and framework being used.