code: function deregisterWish(wish) {
    let indexOfWish = _wishes.indexOf(wish)
    if (!indexOfWish) {
      _each(_wishes, (aWish, index) => {
        // the given parameter could be an id.
        if (wish === aWish.id || wish.id === aWish.id) {
          indexOfWish = index
          wish = aWish
          return false
        }
      })
    }
  
    _wishes.splice(indexOfWish, 1)
    _removeWishIdFromEnteredMagicWords(wish.id)
    return wish
  }
docs: Deregisters the given wish. Removes it from the registry
  and from the _enteredMagicWords map.
  This will delete an _enteredMagicWords listing if this
  is the only wish in the list.
  @param {object|string} wish The wish to deregister
  @returns {wish} The deregistered wish
  @public