setupLesson = function ( canvas ) {

		// only once
		setupLesson = function () {};

		if ( canvas ) {

			canvas.addEventListener( 'webglcontextlost', function () {

				// the default is to do nothing. Preventing the default
				// means allowing context to be restored
				// e.preventDefault();  // can't do this because firefox bug - https://bugzilla.mozilla.org/show_bug.cgi?id=1633280
				addContextLostHTML();

			} );
			/* can't do this because firefox bug - https://bugzilla.mozilla.org/show_bug.cgi?id=1633280
      canvas.addEventListener('webglcontextrestored', function() {
          // just reload the page. Easiest.
          window.location.reload();
      });
      */

		}

		if ( isInIFrame() ) {

			updateCSSIfInIFrame();

		}

	}
Gets a WebGL context.
makes its backing store the size it is displayed.
@param {HTMLCanvasElement} canvas a canvas element.
@memberOf module:webgl-utils