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// Add the allowed characters in an array.
$args = array( '!', '(', ')' );

function maybe_do_allowed_characters( $string, $args ) {

	// Bail if fails string sanity check.
	if ( ! $string && ! is_string( $string ) ) { return; }

	$allowed    = array();
	$defaults   = array(
		'~'   => false,
		'`'   => false,
		'!'   => false,
		'@'   => false,
		'#'   => false,
		'$'   => false,
		'%'   => false,
		'^'   => false,
		'&'   => false,
		'*'   => false,
		'('   => false,
		')'   => false,
		'-'   => false,
		'_'   => false,
		'='   => false,
		'+'   => false,
		'['   => false,
		'{'   => false,
		']'   => false,
		'}'   => false,
		'|'   => false,
		';'   => false,
		':'   => false,
		'\\'  => false,
		'"'   => false,
		','   => false,
		'<'   => false,
		'.'   => false,
		'>'   => false,
		'/'   => false,
		'?'   => false,
	);

	if ( ! empty( $args ) ) {

		foreach ( $args as $char ) {
			$allowed[ $char ] = true;
		}

		$args = wp_parse_args( $allowed, $defaults );

		foreach ( $args as $key => $value ) {
			if ( false === $value ) {
				$string = str_replace( $key, '', $string );
			}
		}
	}

	return $string;
}