post(url, args, cb) {
			return this.poll(null, url, args, cb, true);
		}
Issues a POST request to the given url and invokes the specified
callback function. The function is a wrapper around
{@link LuCI.request#request Request.request()}. The request is
sent using `application/x-www-form-urlencoded` encoding and will
contain a field `token` with the current value of `LuCI.env.token`
by default.

@deprecated
@instance
@memberof LuCI

@param {string} url
The URL to request.

@param {Object<string, string>} [args]
Additional post arguments to append to the request body.

@param {LuCI.requestCallbackFn} cb
The callback function to invoke when the request finishes.

@return {Promise<null>}
Returns a promise resolving to `null` when concluded.