public function __construct( $_field ) {

		$button_defaults = array(
			'classes' => '', // Array or space separated string.
			'icon'    => 'dashicons-plus', // dashicon classname or HTML/String.
			'id'      => $_field['id'] . '-add-new',
			'size'    => 'small',
			'style'   => 'primary',
			'text'    => __( 'Add New', 'lifterlms' ),
		);

		if ( empty( $_field['button'] ) ) {
			$_field['button'] = $button_defaults;
		} else {
			$_field['button'] = wp_parse_args( $_field['button'], $button_defaults );
		}

		$this->field = $_field;

	}