code: function withCallback(source, destination, methods) {
    return promisifyAll(source, destination, methods, thenify.withCallback)
  }
docs: Promisifies all the selected functions in an object and backward compatible with callback.
  
  @param {Object} source the source object for the async functions
  @param {Object} [destination] the destination to set all the promisified methods
  @param {Array} [methods] an array of method names of `source`
  @return {Object}
  @api public