def address_for(machine)
      machine_id = id_for(machine)
      addr, _ = @pool.find do |(addr, id)|
        if id.is_a?(String)
          # Check for old-style UUID values. These should eventually cycle out
          # as machines are destroyed.
          id == machine.id
        else
          id == machine_id
        end
      end

      addr
    end
def address_for(machine)
      machine_id = id_for(machine)
      addr, _ = @pool.find do |(addr, id)|
        if id.is_a?(String)
          # Check for old-style UUID values. These should eventually cycle out
          # as machines are destroyed.
          id == machine.id
        else
          id == machine_id
        end
      end

      addr
    end
Look up the address assigned to a given machine.

 @param machine [Vagrant::Machine]
 @return [IPAddr] the IP address assigned to the machine.
 @return [nil] if the machine has no address assigned.