code: function sealVersion(machineName, versionKey) {
          return co(function*(){
              debug("Attempting to seal the version '%s' of the machine '%s'", versionKey, machineName);
              let info = yield getVersionInfo(machineName, versionKey);
              if(info.isSealed) {
                  throw new Error("Version it already sealed");
              }
  
              debug("Getting manifest");
              let manifest = getManifest();
              let model = getVersionSCXML(machineName, versionKey);
              let isValid = isSCXMLValid(model);
  
              if(!isValid) {
                  throw new Error("The model is not valid.");
              }
  
              info.isSealed = true;
              setVersionInfo(machineName, versionKey, info);
              debug("The version '%s' of the machine '%s' was sealed successfully", versionKey, machineName);
  
          });
      }
docs: Seal a version of a machine
  @method addMachine
  @param {String} machineName The name of the machine
  @param {String} versionKey The key of the version
  @returns {Promise}