    # File lib/fog/rackspace/requests/load_balancers/get_usage.rb, line 5
            def get_usage(options = {})
              if options.has_key? :start_time and options.has_key? :end_time
                query = "?startTime=#{options[:start_time]}&endTime=#{options[:end_time]}"
              else
                query = ''
              end
              request(
                :expects => 200,
                :path => "loadbalancers/usage#{query}",
                :method => 'GET'
              )
             end