function register(element, handlerName, options) {
    var handler = HANDLERS[handlerName.replace(/^\$md./, '')];
    if (!handler) {
      throw new Error('Failed to register element with handler ' + handlerName + '. ' +
      'Available handlers: ' + Object.keys(HANDLERS).join(', '));
    }
    return handler.registerElement(element, options);
  }
Register an element to listen for a handler.
This allows an element to override the default options for a handler.
Additionally, some handlers like drag and hold only dispatch events if
the domEvent happens inside an element that's registered to listen for these events.

@see GestureHandler for how overriding of default options works.
@example $mdGesture.register(myElement, 'drag', { minDistance: 20, horizontal: false })