protected function parse_args() {

		// Sanitize post, user, excluded attempts ids.
		foreach ( array( 'student_id', 'quiz_id', 'exclude' ) as $key ) {
			$this->arguments[ $key ] = $this->sanitize_id_array( $this->arguments[ $key ] );
		}

		// Validate status args.
		$valid_statuses = array_keys( llms_get_quiz_attempt_statuses() );
		foreach ( array( 'status', 'status_exclude' ) as $key ) {

			// Allow single statuses to be passed in as a string.
			if ( is_string( $this->arguments[ $key ] ) ) {
				$this->arguments[ $key ] = array( $this->arguments[ $key ] );
			}

			// Ensure submitted statuses are valid.
			if ( $this->arguments[ $key ] ) {
				$this->arguments[ $key ] = array_intersect( $valid_statuses, $this->arguments[ $key ] );
			}
		}

	}