function elementIdAttribute (id, attributeName) {
    if ((typeof id !== 'string' && typeof id !== 'number') || typeof attributeName !== 'string') {
        throw new ProtocolError('number or type of arguments don\'t agree with elementIdAttribute protocol command')
    }

    return this.requestHandler.create(`/session/:sessionId/element/${id}/attribute/${attributeName}`)
}
Get the value of an element's attribute.

@param {String} ID             ID of a WebElement JSON object to route the command to
@param {String} attributeName  attribute name of element you want to receive

@return {String|null} The value of the attribute, or null if it is not set on the element.

@see  https://w3c.github.io/webdriver/webdriver-spec.html#dfn-get-element-attribute
@type protocol