# File lib/deltacloud.rb, line 327
    def use_driver(driver, opts={})
      if driver
        @api_driver = driver 
        @driver_name = driver
        @features, @entry_points = {}, {}
        discover_entry_points
      end
      @username = opts[:username] if opts[:username]
      @password = opts[:password] if opts[:password]
      @api_provider = opts[:provider] if opts[:provider]
      return self
    end