lib/data-store/index.js
function doCallback (callback, err, arg) {
  if (_.isFunction(callback)) {
    callback(err, arg);
  }
}
function doCallback (callback, err, arg) {
  if (_.isFunction(callback)) {
    callback(err, arg);
  }
}
function doCallback ( callback , err , arg ) { if ( _ . isFunction ( callback ) ) { callback ( err , arg ) ; } }
Calls the given callback with the given arguments, if the callback is defined.

@param   {function|*}    callback
@param   {Error|null}    err
@param   {*}             arg
Calls the given callback with the given arguments if the callback is defined .