old_contents: 'use strict';
  
  const hProto = require('../interface/result.h').prototype;
  const sym = require('../interface/result-sym.h');
  
  
  hProto.or = function ($val) {
      if (!this[sym.isOk]) {
          this[sym.value] = $val;
          this[sym.isOk] = true;
      }
  
      return this;
  };
  
new_contents: 'use strict';
  
  const h = require('../interface/result.h');
  const hProto = h.prototype;
  const sym = require('../interface/result-sym.h');
  
  
  hProto.or = function ($val) {
      return this[sym.isOk]
          ? this
          : h.fromSuccess($val)
      ;
  };
  
subject: fix FP immutability of or()