index.js
function withCallback(source, destination, methods) {
  return promisifyAll(source, destination, methods, thenify.withCallback)
}
function withCallback(source, destination, methods) {
  return promisifyAll(source, destination, methods, thenify.withCallback)
}
function withCallback ( source , destination , methods ) { return promisifyAll ( source , destination , methods , thenify . withCallback ) }
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
Promisifies all the selected functions in an object and backward compatible with callback .