function flush( clbk ) {
	/* eslint-disable no-invalid-this */
	var split = this._buffer;
	if ( split ) {
		debug( 'Processing final split...' );
		split = decode( split, this._encoding );
		this.push( split, this._encoding );
	}
	debug( 'Flushing the stream...' );
	clbk();

	/* eslint-enable no-invalid-this */
}
Implements the `_flush` method.

@private
@param {Callback} clbk - callback to invoke after any final processing