    # File lib/fog/aws/signaturev4.rb, line 42
          def canonical_query_string(query)
            canonical_query_string = []
            for key in (query || {}).keys.sort_by {|k| k.to_s}
              component = "#{Fog::AWS.escape(key.to_s)}=#{Fog::AWS.escape(query[key].to_s)}"
              canonical_query_string << component
            end
            canonical_query_string.join("&")
          end