text: 'use strict';
  
  /** Trade operation type. */
  export const Operation =
      Object.freeze({
          ORDER: 0,
          CANCEL: 1,
          MODIFY: 2,
      });
  
  /** Extension of limit type. */
  export class OperationUtil {
      /** Get stringed value. */
      static toStr = (operation = Operation.ORDER) => {
          switch (operation) {
              case Operation.ORDER:
                  return 'Order';
              case Operation.CANCEL:
                  return 'Cancel';
              case Operation.MODIFY:
                  return 'Modify';
              default:
                  return '';
          }
      }
  }