* Helpers for create methods.

`Promise.reject` returns a promise rejected with the passed `reason`. It is shorthand for the following: ```javascript let promise = new Promis

* Helper fxn to measure ascent and descent. * Adapted from http://stackoverflow.com/a/25355178

* turn a two dimensional array into one dimensional array * @param {Array} arr 2-dimensional array * @return {Array} 1-dimensional array * [[1

`Promise.resolve` returns a promise that will become resolved with the passed `value`. It is shorthand for the following: ```javascript let pro

* Returns a file extension, or another string * if the provided parameter has no extension. * * @param {String} filename * @return {Array}

* Validates clipping params. Per drawImage spec sWidth and sHight cannot be * negative or greater than image intrinsic width and height * @private

VIDEO STUFF

* Helper function for select and selectAll