# File lib/deltacloud.rb, line 439
    def documentation(collection, operation=nil)
      data = {}
      request(:get, "/docs/#{collection}") do |body|
        document = Nokogiri::XML(body)
        if operation
          data[:operation] = operation
          data[:description] = document.xpath('/docs/collection/operations/operation[@name = "'+operation+'"]/description').first.text.strip
          return false unless data[:description]
          data[:params] = []
          (document/"/docs/collection/operations/operation[@name='#{operation}']/parameter").each do |param|
            data[:params] << {
              :name => param['name'],
              :required => param['type'] == 'optional',
              :type => (param/'class').text
            }
          end
        else
          data[:description] = (document/'/docs/collection/description').text
          data[:collection] = collection
          data[:operations] = (document/"/docs/collection/operations/operation").collect{ |o| o['name'] }
        end
      end
      return Documentation.new(self, data)
    end