function touchDown(x, y) {
    if (typeof x !== 'number' || typeof y !== 'number') {
        throw new _ErrorHandler.ProtocolError('number or type of arguments don\'t agree with touchDown command');
    }

    (0, _deprecationWarning2.default)('touchDown', this.options.deprecationWarnings, 'This command is not part of the W3C WebDriver spec and won\'t be supported in ' + 'future versions of the driver. It is recommended to use the touchAction command for this.');

    return this.requestHandler.create('/session/:sessionId/touch/down', { x, y });
}
Finger down on the screen.

This command is deprecated and will be removed soon. Make sure you don't use it in your
automation/test scripts anymore to avoid errors. Please use the
[`touchPerform`](http://webdriver.io/api/mobile/touchPerform.html) command instead.

@param {Number} x  X coordinate on the screen
@param {Number} y  Y coordinate on the screen

@see  https://github.com/SeleniumHQ/selenium/wiki/JsonWireProtocol#sessionsessionidtouchdown
@type protocol
@deprecated