wp-notices.php
public function is_dismissed( $id ) {
		$dismissed = self::$instance->dismissed_notices();
		if ( ! in_array( self::$instance->get_id( $id ), $dismissed ) ) {
			return false;
		}
		return true;
	}
public function is_dismissed( $id ) {
		$dismissed = self::$instance->dismissed_notices();
		if ( ! in_array( self::$instance->get_id( $id ), $dismissed ) ) {
			return false;
		}
		return true;
	}
Check if a notice is dismissed.

@param string $id
@return boolean