# File lib/aws/s3/acl_options.rb, line 160
      def format_grants acl_hash
        grants = {}
        acl_hash.each_pair do |grant,grantees|
          grantees = [grantees] unless grantees.is_a?(Array)
          grants[grant] = grantees.map{|g| format_grantee(g) }.join(', ')
        end
        grants
      end