How many subnets are possible in a network with a /19 cidr?

Consider a list of full names formatted “firstname lastname”, like ["jules verne", "alexandre dumas", "maurice druon"]. write a list comprehension that produces a list with the full names in the format “lastname, firstname”. the resulting list should look like ['verne, jules', 'dumas, alexandre', 'druon, maurice']. the simplest solution may involve a nested comprehension: [ …. for … in [ … for … in … ]].