code: function mergeIntoWithNoDuplicateKeys(one, two) {
      _invariant(one && two && (typeof one === 'undefined' ? 'undefined' : _typeof(one)) === 'object' && (typeof two === 'undefined' ? 'undefined' : _typeof(two)) === 'object', 'mergeIntoWithNoDuplicateKeys(): Cannot merge non-objects.');
  
      for (var key in two) {
        if (two.hasOwnProperty(key)) {
          _invariant(one[key] === undefined, 'mergeIntoWithNoDuplicateKeys(): ' + 'Tried to merge two objects with the same key: `%s`. This conflict ' + 'may be due to a mixin; in particular, this may be caused by two ' + 'getInitialState() or getDefaultProps() methods returning objects ' + 'with clashing keys.', key);
          one[key] = two[key];
        }
      }
      return one;
    }
docs: Merge two objects, but throw if both contain the same key.
  
  @param {object} one The first object, which is mutated.
  @param {object} two The second object
  @return {object} one after it has been mutated to contain everything in two.